kernel - More work on x86_64 low-memory configurations

[dragonfly.git] / sys / platform / pc64 / x86_64 / pmap.c

/*
 * (MPSAFE)
 *
 * Copyright (c) 1991 Regents of the University of California.
 * Copyright (c) 1994 John S. Dyson
 * Copyright (c) 1994 David Greenman
 * Copyright (c) 2003 Peter Wemm
 * Copyright (c) 2005-2008 Alan L. Cox <alc@cs.rice.edu>
 * Copyright (c) 2008, 2009 The DragonFly Project.
 * Copyright (c) 2008, 2009 Jordan Gordeev.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * the Systems Programming Group of the University of Utah Computer
 * Science Department and William Jolitz of UUNET Technologies Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *      from:   @(#)pmap.c      7.7 (Berkeley)  5/12/91
 * $FreeBSD: src/sys/i386/i386/pmap.c,v 1.250.2.18 2002/03/06 22:48:53 silby Exp $
 */

/*
 *      Manages physical address maps.
 *
 *      In addition to hardware address maps, this
 *      module is called upon to provide software-use-only
 *      maps which may or may not be stored in the same
 *      form as hardware maps.  These pseudo-maps are
 *      used to store intermediate results from copy
 *      operations to and from address spaces.
 *
 *      Since the information managed by this module is
 *      also stored by the logical address mapping module,
 *      this module may throw away valid virtual-to-physical
 *      mappings at almost any time.  However, invalidations
 *      of virtual-to-physical mappings must be done as
 *      requested.
 *
 *      In order to cope with hardware architectures which
 *      make virtual-to-physical map invalidates expensive,
 *      this module may delay invalidate or reduced protection
 *      operations until such time as they are actually
 *      necessary.  This module is given full information as
 *      to which processors are currently using which maps,
 *      and to when physical maps must be made correct.
 */

#if JG
#include "opt_disable_pse.h"
#include "opt_pmap.h"
#endif
#include "opt_msgbuf.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/msgbuf.h>
#include <sys/vmmeter.h>
#include <sys/mman.h>

#include <vm/vm.h>
#include <vm/vm_param.h>
#include <sys/sysctl.h>
#include <sys/lock.h>
#include <vm/vm_kern.h>
#include <vm/vm_page.h>
#include <vm/vm_map.h>
#include <vm/vm_object.h>
#include <vm/vm_extern.h>
#include <vm/vm_pageout.h>
#include <vm/vm_pager.h>
#include <vm/vm_zone.h>

#include <sys/user.h>
#include <sys/thread2.h>
#include <sys/sysref2.h>

#include <machine/cputypes.h>
#include <machine/md_var.h>
#include <machine/specialreg.h>
#include <machine/smp.h>
#include <machine_base/apic/apicreg.h>
#include <machine/globaldata.h>
#include <machine/pmap.h>
#include <machine/pmap_inval.h>

#include <ddb/ddb.h>

#define PMAP_KEEP_PDIRS
#ifndef PMAP_SHPGPERPROC
#define PMAP_SHPGPERPROC 200
#endif

#if defined(DIAGNOSTIC)
#define PMAP_DIAGNOSTIC
#endif

#define MINPV 2048

/*
 * Get PDEs and PTEs for user/kernel address space
 */
static pd_entry_t *pmap_pde(pmap_t pmap, vm_offset_t va);
#define pdir_pde(m, v) (m[(vm_offset_t)(v) >> PDRSHIFT])

#define pmap_pde_v(pte)         ((*(pd_entry_t *)pte & PG_V) != 0)
#define pmap_pte_w(pte)         ((*(pt_entry_t *)pte & PG_W) != 0)
#define pmap_pte_m(pte)         ((*(pt_entry_t *)pte & PG_M) != 0)
#define pmap_pte_u(pte)         ((*(pt_entry_t *)pte & PG_A) != 0)
#define pmap_pte_v(pte)         ((*(pt_entry_t *)pte & PG_V) != 0)


/*
 * Given a map and a machine independent protection code,
 * convert to a vax protection code.
 */
#define pte_prot(m, p)          \
        (protection_codes[p & (VM_PROT_READ|VM_PROT_WRITE|VM_PROT_EXECUTE)])
static int protection_codes[8];

struct pmap kernel_pmap;
static TAILQ_HEAD(,pmap)        pmap_list = TAILQ_HEAD_INITIALIZER(pmap_list);

vm_paddr_t avail_start;         /* PA of first available physical page */
vm_paddr_t avail_end;           /* PA of last available physical page */
vm_offset_t virtual2_start;     /* cutout free area prior to kernel start */
vm_offset_t virtual2_end;
vm_offset_t virtual_start;      /* VA of first avail page (after kernel bss) */
vm_offset_t virtual_end;        /* VA of last avail page (end of kernel AS) */
vm_offset_t KvaStart;           /* VA start of KVA space */
vm_offset_t KvaEnd;             /* VA end of KVA space (non-inclusive) */
vm_offset_t KvaSize;            /* max size of kernel virtual address space */
static boolean_t pmap_initialized = FALSE;      /* Has pmap_init completed? */
static int pgeflag;             /* PG_G or-in */
static int pseflag;             /* PG_PS or-in */

static vm_object_t kptobj;

static int ndmpdp;
static vm_paddr_t dmaplimit;
static int nkpt;
vm_offset_t kernel_vm_end = VM_MIN_KERNEL_ADDRESS;

static uint64_t KPTbase;
static uint64_t KPTphys;
static uint64_t KPDphys;        /* phys addr of kernel level 2 */
static uint64_t KPDbase;        /* phys addr of kernel level 2 @ KERNBASE */
uint64_t KPDPphys;      /* phys addr of kernel level 3 */
uint64_t KPML4phys;     /* phys addr of kernel level 4 */

static uint64_t DMPDphys;       /* phys addr of direct mapped level 2 */
static uint64_t DMPDPphys;      /* phys addr of direct mapped level 3 */

/*
 * Data for the pv entry allocation mechanism
 */
static vm_zone_t pvzone;
static struct vm_zone pvzone_store;
static struct vm_object pvzone_obj;
static int pv_entry_count=0, pv_entry_max=0, pv_entry_high_water=0;
static int pmap_pagedaemon_waken = 0;
static struct pv_entry *pvinit;

/*
 * All those kernel PT submaps that BSD is so fond of
 */
pt_entry_t *CMAP1 = 0, *ptmmap;
caddr_t CADDR1 = 0, ptvmmap = 0;
static pt_entry_t *msgbufmap;
struct msgbuf *msgbufp=0;

/*
 * Crashdump maps.
 */
static pt_entry_t *pt_crashdumpmap;
static caddr_t crashdumpmap;

extern pt_entry_t *SMPpt;
extern uint64_t SMPptpa;

#define DISABLE_PSE

static pv_entry_t get_pv_entry (void);
static void i386_protection_init (void);
static void create_pagetables(vm_paddr_t *firstaddr);
static void pmap_remove_all (vm_page_t m);
static int  pmap_remove_pte (struct pmap *pmap, pt_entry_t *ptq,
                                vm_offset_t sva, pmap_inval_info_t info);
static void pmap_remove_page (struct pmap *pmap, 
                                vm_offset_t va, pmap_inval_info_t info);
static int  pmap_remove_entry (struct pmap *pmap, vm_page_t m,
                                vm_offset_t va, pmap_inval_info_t info);
static boolean_t pmap_testbit (vm_page_t m, int bit);
static void pmap_insert_entry (pmap_t pmap, vm_offset_t va,
                                vm_page_t mpte, vm_page_t m);

static vm_page_t pmap_allocpte (pmap_t pmap, vm_offset_t va);

static int pmap_release_free_page (pmap_t pmap, vm_page_t p);
static vm_page_t _pmap_allocpte (pmap_t pmap, vm_pindex_t ptepindex);
static pt_entry_t * pmap_pte_quick (pmap_t pmap, vm_offset_t va);
static vm_page_t pmap_page_lookup (vm_object_t object, vm_pindex_t pindex);
static int _pmap_unwire_pte_hold(pmap_t pmap, vm_offset_t va, vm_page_t m,
                                pmap_inval_info_t info);
static int pmap_unuse_pt (pmap_t, vm_offset_t, vm_page_t, pmap_inval_info_t);
static vm_offset_t pmap_kmem_choose(vm_offset_t addr);

static unsigned pdir4mb;

/*
 * Move the kernel virtual free pointer to the next
 * 2MB.  This is used to help improve performance
 * by using a large (2MB) page for much of the kernel
 * (.text, .data, .bss)
 */
static
vm_offset_t
pmap_kmem_choose(vm_offset_t addr)
{
        vm_offset_t newaddr = addr;

        newaddr = (addr + (NBPDR - 1)) & ~(NBPDR - 1);
        return newaddr;
}

/*
 * pmap_pte_quick:
 *
 *      Super fast pmap_pte routine best used when scanning the pv lists.
 *      This eliminates many course-grained invltlb calls.  Note that many of
 *      the pv list scans are across different pmaps and it is very wasteful
 *      to do an entire invltlb when checking a single mapping.
 *
 *      Should only be called while in a critical section.
 */
static __inline pt_entry_t *pmap_pte(pmap_t pmap, vm_offset_t va);

static
pt_entry_t *
pmap_pte_quick(pmap_t pmap, vm_offset_t va)
{
        return pmap_pte(pmap, va);
}

/* Return a non-clipped PD index for a given VA */
static __inline
vm_pindex_t
pmap_pde_pindex(vm_offset_t va)
{
        return va >> PDRSHIFT;
}

/* Return various clipped indexes for a given VA */
static __inline
vm_pindex_t
pmap_pte_index(vm_offset_t va)
{

        return ((va >> PAGE_SHIFT) & ((1ul << NPTEPGSHIFT) - 1));
}

static __inline
vm_pindex_t
pmap_pde_index(vm_offset_t va)
{

        return ((va >> PDRSHIFT) & ((1ul << NPDEPGSHIFT) - 1));
}

static __inline
vm_pindex_t
pmap_pdpe_index(vm_offset_t va)
{

        return ((va >> PDPSHIFT) & ((1ul << NPDPEPGSHIFT) - 1));
}

static __inline
vm_pindex_t
pmap_pml4e_index(vm_offset_t va)
{

        return ((va >> PML4SHIFT) & ((1ul << NPML4EPGSHIFT) - 1));
}

/* Return a pointer to the PML4 slot that corresponds to a VA */
static __inline
pml4_entry_t *
pmap_pml4e(pmap_t pmap, vm_offset_t va)
{

        return (&pmap->pm_pml4[pmap_pml4e_index(va)]);
}

/* Return a pointer to the PDP slot that corresponds to a VA */
static __inline
pdp_entry_t *
pmap_pml4e_to_pdpe(pml4_entry_t *pml4e, vm_offset_t va)
{
        pdp_entry_t *pdpe;

        pdpe = (pdp_entry_t *)PHYS_TO_DMAP(*pml4e & PG_FRAME);
        return (&pdpe[pmap_pdpe_index(va)]);
}

/* Return a pointer to the PDP slot that corresponds to a VA */
static __inline
pdp_entry_t *
pmap_pdpe(pmap_t pmap, vm_offset_t va)
{
        pml4_entry_t *pml4e;

        pml4e = pmap_pml4e(pmap, va);
        if ((*pml4e & PG_V) == 0)
                return NULL;
        return (pmap_pml4e_to_pdpe(pml4e, va));
}

/* Return a pointer to the PD slot that corresponds to a VA */
static __inline
pd_entry_t *
pmap_pdpe_to_pde(pdp_entry_t *pdpe, vm_offset_t va)
{
        pd_entry_t *pde;

        pde = (pd_entry_t *)PHYS_TO_DMAP(*pdpe & PG_FRAME);
        return (&pde[pmap_pde_index(va)]);
}

/* Return a pointer to the PD slot that corresponds to a VA */
static __inline
pd_entry_t *
pmap_pde(pmap_t pmap, vm_offset_t va)
{
        pdp_entry_t *pdpe;

        pdpe = pmap_pdpe(pmap, va);
        if (pdpe == NULL || (*pdpe & PG_V) == 0)
                 return NULL;
        return (pmap_pdpe_to_pde(pdpe, va));
}

/* Return a pointer to the PT slot that corresponds to a VA */
static __inline
pt_entry_t *
pmap_pde_to_pte(pd_entry_t *pde, vm_offset_t va)
{
        pt_entry_t *pte;

        pte = (pt_entry_t *)PHYS_TO_DMAP(*pde & PG_FRAME);
        return (&pte[pmap_pte_index(va)]);
}

/* Return a pointer to the PT slot that corresponds to a VA */
static __inline
pt_entry_t *
pmap_pte(pmap_t pmap, vm_offset_t va)
{
        pd_entry_t *pde;

        pde = pmap_pde(pmap, va);
        if (pde == NULL || (*pde & PG_V) == 0)
                return NULL;
        if ((*pde & PG_PS) != 0)        /* compat with i386 pmap_pte() */
                return ((pt_entry_t *)pde);
        return (pmap_pde_to_pte(pde, va));
}

static __inline
pt_entry_t *
vtopte(vm_offset_t va)
{
        uint64_t mask = ((1ul << (NPTEPGSHIFT + NPDEPGSHIFT + NPDPEPGSHIFT + NPML4EPGSHIFT)) - 1);

        return (PTmap + ((va >> PAGE_SHIFT) & mask));
}

static __inline
pd_entry_t *
vtopde(vm_offset_t va)
{
        uint64_t mask = ((1ul << (NPDEPGSHIFT + NPDPEPGSHIFT + NPML4EPGSHIFT)) - 1);

        return (PDmap + ((va >> PDRSHIFT) & mask));
}

static uint64_t
allocpages(vm_paddr_t *firstaddr, int n)
{
        uint64_t ret;

        ret = *firstaddr;
        bzero((void *)ret, n * PAGE_SIZE);
        *firstaddr += n * PAGE_SIZE;
        return (ret);
}

static
void
create_pagetables(vm_paddr_t *firstaddr)
{
        int i;

        /*
         * We are running (mostly) V=P at this point
         *
         * Calculate NKPT - number of kernel page tables.  We have to
         * accomodoate prealloction of the vm_page_array, dump bitmap,
         * MSGBUF_SIZE, and other stuff.  Be generous.
         *
         * Maxmem is in pages.
         */
        ndmpdp = (ptoa(Maxmem) + NBPDP - 1) >> PDPSHIFT;
        if (ndmpdp < 4)         /* Minimum 4GB of dirmap */
                ndmpdp = 4;

        nkpt = (Maxmem * sizeof(struct vm_page) + NBPDR - 1) / NBPDR;
        nkpt += ((nkpt + nkpt + 1 + NKPML4E + NKPDPE + NDMPML4E + ndmpdp) +
                511) / 512;
        nkpt += 128;

        /*
         * Allocate pages
         */
        KPTbase = allocpages(firstaddr, nkpt);
        KPTphys = allocpages(firstaddr, nkpt);
        KPML4phys = allocpages(firstaddr, 1);
        KPDPphys = allocpages(firstaddr, NKPML4E);

        /*
         * Calculate the page directory base for KERNBASE,
         * that is where we start populating the page table pages.
         * Basically this is the end - 2.
         */
        KPDphys = allocpages(firstaddr, NKPDPE);
        KPDbase = KPDphys + ((NKPDPE - (NPDPEPG - KPDPI)) << PAGE_SHIFT);

        DMPDPphys = allocpages(firstaddr, NDMPML4E);
        if ((amd_feature & AMDID_PAGE1GB) == 0)
                DMPDphys = allocpages(firstaddr, ndmpdp);
        dmaplimit = (vm_paddr_t)ndmpdp << PDPSHIFT;

        /*
         * Fill in the underlying page table pages for the area around
         * KERNBASE.  This remaps low physical memory to KERNBASE.
         *
         * Read-only from zero to physfree
         * XXX not fully used, underneath 2M pages
         */
        for (i = 0; (i << PAGE_SHIFT) < *firstaddr; i++) {
                ((pt_entry_t *)KPTbase)[i] = i << PAGE_SHIFT;
                ((pt_entry_t *)KPTbase)[i] |= PG_RW | PG_V | PG_G;
        }

        /*
         * Now map the initial kernel page tables.  One block of page
         * tables is placed at the beginning of kernel virtual memory,
         * and another block is placed at KERNBASE to map the kernel binary,
         * data, bss, and initial pre-allocations.
         */
        for (i = 0; i < nkpt; i++) {
                ((pd_entry_t *)KPDbase)[i] = KPTbase + (i << PAGE_SHIFT);
                ((pd_entry_t *)KPDbase)[i] |= PG_RW | PG_V;
        }
        for (i = 0; i < nkpt; i++) {
                ((pd_entry_t *)KPDphys)[i] = KPTphys + (i << PAGE_SHIFT);
                ((pd_entry_t *)KPDphys)[i] |= PG_RW | PG_V;
        }

        /*
         * Map from zero to end of allocations using 2M pages as an
         * optimization.  This will bypass some of the KPTBase pages
         * above in the KERNBASE area.
         */
        for (i = 0; (i << PDRSHIFT) < *firstaddr; i++) {
                ((pd_entry_t *)KPDbase)[i] = i << PDRSHIFT;
                ((pd_entry_t *)KPDbase)[i] |= PG_RW | PG_V | PG_PS | PG_G;
        }

        /*
         * And connect up the PD to the PDP.  The kernel pmap is expected
         * to pre-populate all of its PDs.  See NKPDPE in vmparam.h.
         */
        for (i = 0; i < NKPDPE; i++) {
                ((pdp_entry_t *)KPDPphys)[NPDPEPG - NKPDPE + i] =
                                KPDphys + (i << PAGE_SHIFT);
                ((pdp_entry_t *)KPDPphys)[NPDPEPG - NKPDPE + i] |=
                                PG_RW | PG_V | PG_U;
        }

        /* Now set up the direct map space using either 2MB or 1GB pages */
        /* Preset PG_M and PG_A because demotion expects it */
        if ((amd_feature & AMDID_PAGE1GB) == 0) {
                for (i = 0; i < NPDEPG * ndmpdp; i++) {
                        ((pd_entry_t *)DMPDphys)[i] = (vm_paddr_t)i << PDRSHIFT;
                        ((pd_entry_t *)DMPDphys)[i] |= PG_RW | PG_V | PG_PS |
                            PG_G | PG_M | PG_A;
                }
                /* And the direct map space's PDP */
                for (i = 0; i < ndmpdp; i++) {
                        ((pdp_entry_t *)DMPDPphys)[i] = DMPDphys +
                            (i << PAGE_SHIFT);
                        ((pdp_entry_t *)DMPDPphys)[i] |= PG_RW | PG_V | PG_U;
                }
        } else {
                for (i = 0; i < ndmpdp; i++) {
                        ((pdp_entry_t *)DMPDPphys)[i] =
                            (vm_paddr_t)i << PDPSHIFT;
                        ((pdp_entry_t *)DMPDPphys)[i] |= PG_RW | PG_V | PG_PS |
                            PG_G | PG_M | PG_A;
                }
        }

        /* And recursively map PML4 to itself in order to get PTmap */
        ((pdp_entry_t *)KPML4phys)[PML4PML4I] = KPML4phys;
        ((pdp_entry_t *)KPML4phys)[PML4PML4I] |= PG_RW | PG_V | PG_U;

        /* Connect the Direct Map slot up to the PML4 */
        ((pdp_entry_t *)KPML4phys)[DMPML4I] = DMPDPphys;
        ((pdp_entry_t *)KPML4phys)[DMPML4I] |= PG_RW | PG_V | PG_U;

        /* Connect the KVA slot up to the PML4 */
        ((pdp_entry_t *)KPML4phys)[KPML4I] = KPDPphys;
        ((pdp_entry_t *)KPML4phys)[KPML4I] |= PG_RW | PG_V | PG_U;
}

/*
 *      Bootstrap the system enough to run with virtual memory.
 *
 *      On the i386 this is called after mapping has already been enabled
 *      and just syncs the pmap module with what has already been done.
 *      [We can't call it easily with mapping off since the kernel is not
 *      mapped with PA == VA, hence we would have to relocate every address
 *      from the linked base (virtual) address "KERNBASE" to the actual
 *      (physical) address starting relative to 0]
 */
void
pmap_bootstrap(vm_paddr_t *firstaddr)
{
        vm_offset_t va;
        pt_entry_t *pte;
        struct mdglobaldata *gd;
        int pg;

        KvaStart = VM_MIN_KERNEL_ADDRESS;
        KvaEnd = VM_MAX_KERNEL_ADDRESS;
        KvaSize = KvaEnd - KvaStart;

        avail_start = *firstaddr;

        /*
         * Create an initial set of page tables to run the kernel in.
         */
        create_pagetables(firstaddr);

        virtual2_start = KvaStart;
        virtual2_end = PTOV_OFFSET;

        virtual_start = (vm_offset_t) PTOV_OFFSET + *firstaddr;
        virtual_start = pmap_kmem_choose(virtual_start);

        virtual_end = VM_MAX_KERNEL_ADDRESS;

        /* XXX do %cr0 as well */
        load_cr4(rcr4() | CR4_PGE | CR4_PSE);
        load_cr3(KPML4phys);

        /*
         * Initialize protection array.
         */
        i386_protection_init();

        /*
         * The kernel's pmap is statically allocated so we don't have to use
         * pmap_create, which is unlikely to work correctly at this part of
         * the boot sequence (XXX and which no longer exists).
         */
        kernel_pmap.pm_pml4 = (pdp_entry_t *) (PTOV_OFFSET + KPML4phys);
        kernel_pmap.pm_count = 1;
        kernel_pmap.pm_active = (cpumask_t)-1 & ~CPUMASK_LOCK;
        TAILQ_INIT(&kernel_pmap.pm_pvlist);

        /*
         * Reserve some special page table entries/VA space for temporary
         * mapping of pages.
         */
#define SYSMAP(c, p, v, n)      \
        v = (c)va; va += ((n)*PAGE_SIZE); p = pte; pte += (n);

        va = virtual_start;
        pte = vtopte(va);

        /*
         * CMAP1/CMAP2 are used for zeroing and copying pages.
         */
        SYSMAP(caddr_t, CMAP1, CADDR1, 1)

        /*
         * Crashdump maps.
         */
        SYSMAP(caddr_t, pt_crashdumpmap, crashdumpmap, MAXDUMPPGS);

        /*
         * ptvmmap is used for reading arbitrary physical pages via
         * /dev/mem.
         */
        SYSMAP(caddr_t, ptmmap, ptvmmap, 1)

        /*
         * msgbufp is used to map the system message buffer.
         * XXX msgbufmap is not used.
         */
        SYSMAP(struct msgbuf *, msgbufmap, msgbufp,
               atop(round_page(MSGBUF_SIZE)))

        virtual_start = va;

        *CMAP1 = 0;

        /*
         * PG_G is terribly broken on SMP because we IPI invltlb's in some
         * cases rather then invl1pg.  Actually, I don't even know why it
         * works under UP because self-referential page table mappings
         */
#ifdef SMP
        pgeflag = 0;
#else
        if (cpu_feature & CPUID_PGE)
                pgeflag = PG_G;
#endif
        
/*
 * Initialize the 4MB page size flag
 */
        pseflag = 0;
/*
 * The 4MB page version of the initial
 * kernel page mapping.
 */
        pdir4mb = 0;

#if !defined(DISABLE_PSE)
        if (cpu_feature & CPUID_PSE) {
                pt_entry_t ptditmp;
                /*
                 * Note that we have enabled PSE mode
                 */
                pseflag = PG_PS;
                ptditmp = *(PTmap + x86_64_btop(KERNBASE));
                ptditmp &= ~(NBPDR - 1);
                ptditmp |= PG_V | PG_RW | PG_PS | PG_U | pgeflag;
                pdir4mb = ptditmp;

#ifndef SMP
                /*
                 * Enable the PSE mode.  If we are SMP we can't do this
                 * now because the APs will not be able to use it when
                 * they boot up.
                 */
                load_cr4(rcr4() | CR4_PSE);

                /*
                 * We can do the mapping here for the single processor
                 * case.  We simply ignore the old page table page from
                 * now on.
                 */
                /*
                 * For SMP, we still need 4K pages to bootstrap APs,
                 * PSE will be enabled as soon as all APs are up.
                 */
                PTD[KPTDI] = (pd_entry_t)ptditmp;
                cpu_invltlb();
#endif
        }
#endif

        /*
         * We need to finish setting up the globaldata page for the BSP.
         * locore has already populated the page table for the mdglobaldata
         * portion.
         */
        pg = MDGLOBALDATA_BASEALLOC_PAGES;
        gd = &CPU_prvspace[0].mdglobaldata;
        gd->gd_CMAP1 = &SMPpt[pg + 0];
        gd->gd_CMAP2 = &SMPpt[pg + 1];
        gd->gd_CMAP3 = &SMPpt[pg + 2];
        gd->gd_PMAP1 = &SMPpt[pg + 3];
        gd->gd_CADDR1 = CPU_prvspace[0].CPAGE1;
        gd->gd_CADDR2 = CPU_prvspace[0].CPAGE2;
        gd->gd_CADDR3 = CPU_prvspace[0].CPAGE3;
        gd->gd_PADDR1 = (pt_entry_t *)CPU_prvspace[0].PPAGE1;

        cpu_invltlb();
}

#ifdef SMP
/*
 * Set 4mb pdir for mp startup
 */
void
pmap_set_opt(void)
{
        if (pseflag && (cpu_feature & CPUID_PSE)) {
                load_cr4(rcr4() | CR4_PSE);
                if (pdir4mb && mycpu->gd_cpuid == 0) {  /* only on BSP */
                        cpu_invltlb();
                }
        }
}
#endif

/*
 *      Initialize the pmap module.
 *      Called by vm_init, to initialize any structures that the pmap
 *      system needs to map virtual memory.
 *      pmap_init has been enhanced to support in a fairly consistant
 *      way, discontiguous physical memory.
 */
void
pmap_init(void)
{
        int i;
        int initial_pvs;

        /*
         * object for kernel page table pages
         */
        /* JG I think the number can be arbitrary */
        kptobj = vm_object_allocate(OBJT_DEFAULT, 5);

        /*
         * Allocate memory for random pmap data structures.  Includes the
         * pv_head_table.
         */

        for(i = 0; i < vm_page_array_size; i++) {
                vm_page_t m;

                m = &vm_page_array[i];
                TAILQ_INIT(&m->md.pv_list);
                m->md.pv_list_count = 0;
        }

        /*
         * init the pv free list
         */
        initial_pvs = vm_page_array_size;
        if (initial_pvs < MINPV)
                initial_pvs = MINPV;
        pvzone = &pvzone_store;
        pvinit = (void *)kmem_alloc(&kernel_map,
                                    initial_pvs * sizeof (struct pv_entry));
        zbootinit(pvzone, "PV ENTRY", sizeof (struct pv_entry),
                  pvinit, initial_pvs);

        /*
         * Now it is safe to enable pv_table recording.
         */
        pmap_initialized = TRUE;
#ifdef SMP
        lapic = pmap_mapdev_uncacheable(cpu_apic_address, sizeof(struct LAPIC));
#endif
}

/*
 * Initialize the address space (zone) for the pv_entries.  Set a
 * high water mark so that the system can recover from excessive
 * numbers of pv entries.
 */
void
pmap_init2(void)
{
        int shpgperproc = PMAP_SHPGPERPROC;
        int entry_max;

        TUNABLE_INT_FETCH("vm.pmap.shpgperproc", &shpgperproc);
        pv_entry_max = shpgperproc * maxproc + vm_page_array_size;
        TUNABLE_INT_FETCH("vm.pmap.pv_entries", &pv_entry_max);
        pv_entry_high_water = 9 * (pv_entry_max / 10);

        /*
         * Subtract out pages already installed in the zone (hack)
         */
        entry_max = pv_entry_max - vm_page_array_size;
        if (entry_max <= 0)
                entry_max = 1;

        zinitna(pvzone, &pvzone_obj, NULL, 0, entry_max, ZONE_INTERRUPT, 1);
}


/***************************************************
 * Low level helper routines.....
 ***************************************************/

#if defined(PMAP_DIAGNOSTIC)

/*
 * This code checks for non-writeable/modified pages.
 * This should be an invalid condition.
 */
static
int
pmap_nw_modified(pt_entry_t pte)
{
        if ((pte & (PG_M|PG_RW)) == PG_M)
                return 1;
        else
                return 0;
}
#endif


/*
 * this routine defines the region(s) of memory that should
 * not be tested for the modified bit.
 */
static __inline
int
pmap_track_modified(vm_offset_t va)
{
        if ((va < clean_sva) || (va >= clean_eva)) 
                return 1;
        else
                return 0;
}

/*
 * Extract the physical page address associated with the map/VA pair.
 *
 * The caller must hold vm_token if non-blocking operation is desired.
 */
vm_paddr_t 
pmap_extract(pmap_t pmap, vm_offset_t va)
{
        vm_paddr_t rtval;
        pt_entry_t *pte;
        pd_entry_t pde, *pdep;

        lwkt_gettoken(&vm_token);
        rtval = 0;
        pdep = pmap_pde(pmap, va);
        if (pdep != NULL) {
                pde = *pdep;
                if (pde) {
                        if ((pde & PG_PS) != 0) {
                                rtval = (pde & PG_PS_FRAME) | (va & PDRMASK);
                        } else {
                                pte = pmap_pde_to_pte(pdep, va);
                                rtval = (*pte & PG_FRAME) | (va & PAGE_MASK);
                        }
                }
        }
        lwkt_reltoken(&vm_token);
        return rtval;
}

/*
 * Extract the physical page address associated kernel virtual address.
 */
vm_paddr_t
pmap_kextract(vm_offset_t va)
{
        pd_entry_t pde;
        vm_paddr_t pa;

        if (va >= DMAP_MIN_ADDRESS && va < DMAP_MAX_ADDRESS) {
                pa = DMAP_TO_PHYS(va);
        } else {
                pde = *vtopde(va);
                if (pde & PG_PS) {
                        pa = (pde & PG_PS_FRAME) | (va & PDRMASK);
                } else {
                        /*
                         * Beware of a concurrent promotion that changes the
                         * PDE at this point!  For example, vtopte() must not
                         * be used to access the PTE because it would use the
                         * new PDE.  It is, however, safe to use the old PDE
                         * because the page table page is preserved by the
                         * promotion.
                         */
                        pa = *pmap_pde_to_pte(&pde, va);
                        pa = (pa & PG_FRAME) | (va & PAGE_MASK);
                }
        }
        return pa;
}

/***************************************************
 * Low level mapping routines.....
 ***************************************************/

/*
 * Routine: pmap_kenter
 * Function:
 *      Add a wired page to the KVA
 *      NOTE! note that in order for the mapping to take effect -- you
 *      should do an invltlb after doing the pmap_kenter().
 */
void 
pmap_kenter(vm_offset_t va, vm_paddr_t pa)
{
        pt_entry_t *pte;
        pt_entry_t npte;
        pmap_inval_info info;

        pmap_inval_init(&info);
        npte = pa | PG_RW | PG_V | pgeflag;
        pte = vtopte(va);
        pmap_inval_interlock(&info, &kernel_pmap, va);
        *pte = npte;
        pmap_inval_deinterlock(&info, &kernel_pmap);
        pmap_inval_done(&info);
}

/*
 * Routine: pmap_kenter_quick
 * Function:
 *      Similar to pmap_kenter(), except we only invalidate the
 *      mapping on the current CPU.
 */
void
pmap_kenter_quick(vm_offset_t va, vm_paddr_t pa)
{
        pt_entry_t *pte;
        pt_entry_t npte;

        npte = pa | PG_RW | PG_V | pgeflag;
        pte = vtopte(va);
        *pte = npte;
        cpu_invlpg((void *)va);
}

void
pmap_kenter_sync(vm_offset_t va)
{
        pmap_inval_info info;

        pmap_inval_init(&info);
        pmap_inval_interlock(&info, &kernel_pmap, va);
        pmap_inval_deinterlock(&info, &kernel_pmap);
        pmap_inval_done(&info);
}

void
pmap_kenter_sync_quick(vm_offset_t va)
{
        cpu_invlpg((void *)va);
}

/*
 * remove a page from the kernel pagetables
 */
void
pmap_kremove(vm_offset_t va)
{
        pt_entry_t *pte;
        pmap_inval_info info;

        pmap_inval_init(&info);
        pte = vtopte(va);
        pmap_inval_interlock(&info, &kernel_pmap, va);
        *pte = 0;
        pmap_inval_deinterlock(&info, &kernel_pmap);
        pmap_inval_done(&info);
}

void
pmap_kremove_quick(vm_offset_t va)
{
        pt_entry_t *pte;
        pte = vtopte(va);
        *pte = 0;
        cpu_invlpg((void *)va);
}

/*
 * XXX these need to be recoded.  They are not used in any critical path.
 */
void
pmap_kmodify_rw(vm_offset_t va)
{
        *vtopte(va) |= PG_RW;
        cpu_invlpg((void *)va);
}

void
pmap_kmodify_nc(vm_offset_t va)
{
        *vtopte(va) |= PG_N;
        cpu_invlpg((void *)va);
}

/*
 * Used to map a range of physical addresses into kernel virtual
 * address space during the low level boot, typically to map the
 * dump bitmap, message buffer, and vm_page_array.
 *
 * These mappings are typically made at some pointer after the end of the
 * kernel text+data.
 *
 * We could return PHYS_TO_DMAP(start) here and not allocate any
 * via (*virtp), but then kmem from userland and kernel dumps won't
 * have access to the related pointers.
 */
vm_offset_t
pmap_map(vm_offset_t *virtp, vm_paddr_t start, vm_paddr_t end, int prot)
{
        vm_offset_t va;
        vm_offset_t va_start;

        /*return PHYS_TO_DMAP(start);*/

        va_start = *virtp;
        va = va_start;

        while (start < end) {
                pmap_kenter_quick(va, start);
                va += PAGE_SIZE;
                start += PAGE_SIZE;
        }
        *virtp = va;
        return va_start;
}


/*
 * Add a list of wired pages to the kva
 * this routine is only used for temporary
 * kernel mappings that do not need to have
 * page modification or references recorded.
 * Note that old mappings are simply written
 * over.  The page *must* be wired.
 */
void
pmap_qenter(vm_offset_t va, vm_page_t *m, int count)
{
        vm_offset_t end_va;

        end_va = va + count * PAGE_SIZE;
                
        while (va < end_va) {
                pt_entry_t *pte;

                pte = vtopte(va);
                *pte = VM_PAGE_TO_PHYS(*m) | PG_RW | PG_V | pgeflag;
                cpu_invlpg((void *)va);
                va += PAGE_SIZE;
                m++;
        }
#ifdef SMP
        smp_invltlb();  /* XXX */
#endif
}

/*
 * This routine jerks page mappings from the
 * kernel -- it is meant only for temporary mappings.
 *
 * MPSAFE, INTERRUPT SAFE (cluster callback)
 */
void
pmap_qremove(vm_offset_t va, int count)
{
        vm_offset_t end_va;

        end_va = va + count * PAGE_SIZE;

        while (va < end_va) {
                pt_entry_t *pte;

                pte = vtopte(va);
                *pte = 0;
                cpu_invlpg((void *)va);
                va += PAGE_SIZE;
        }
#ifdef SMP
        smp_invltlb();
#endif
}

/*
 * This routine works like vm_page_lookup() but also blocks as long as the
 * page is busy.  This routine does not busy the page it returns.
 *
 * Unless the caller is managing objects whos pages are in a known state,
 * the call should be made with a critical section held so the page's object
 * association remains valid on return.
 */
static
vm_page_t
pmap_page_lookup(vm_object_t object, vm_pindex_t pindex)
{
        vm_page_t m;

        do {
                m = vm_page_lookup(object, pindex);
        } while (m && vm_page_sleep_busy(m, FALSE, "pplookp"));

        return(m);
}

/*
 * Create a new thread and optionally associate it with a (new) process.
 * NOTE! the new thread's cpu may not equal the current cpu.
 */
void
pmap_init_thread(thread_t td)
{
        /* enforce pcb placement */
        td->td_pcb = (struct pcb *)(td->td_kstack + td->td_kstack_size) - 1;
        td->td_savefpu = &td->td_pcb->pcb_save;
        td->td_sp = (char *)td->td_pcb - 16; /* JG is -16 needed on x86_64? */
}

/*
 * This routine directly affects the fork perf for a process.
 */
void
pmap_init_proc(struct proc *p)
{
}

/*
 * Dispose the UPAGES for a process that has exited.
 * This routine directly impacts the exit perf of a process.
 */
void
pmap_dispose_proc(struct proc *p)
{
        KASSERT(p->p_lock == 0, ("attempt to dispose referenced proc! %p", p));
}

/***************************************************
 * Page table page management routines.....
 ***************************************************/

/*
 * This routine unholds page table pages, and if the hold count
 * drops to zero, then it decrements the wire count.
 */
static __inline
int
pmap_unwire_pte_hold(pmap_t pmap, vm_offset_t va, vm_page_t m,
                     pmap_inval_info_t info)
{
        KKASSERT(m->hold_count > 0);
        if (m->hold_count > 1) {
                vm_page_unhold(m);
                return 0;
        } else {
                return _pmap_unwire_pte_hold(pmap, va, m, info);
        }
}

static
int
_pmap_unwire_pte_hold(pmap_t pmap, vm_offset_t va, vm_page_t m,
                      pmap_inval_info_t info)
{
        /* 
         * Wait until we can busy the page ourselves.  We cannot have
         * any active flushes if we block.  We own one hold count on the
         * page so it cannot be freed out from under us.
         */
        if (m->flags & PG_BUSY) {
                pmap_inval_flush(info);
                while (vm_page_sleep_busy(m, FALSE, "pmuwpt"))
                        ;
        }
        KASSERT(m->queue == PQ_NONE,
                ("_pmap_unwire_pte_hold: %p->queue != PQ_NONE", m));

        /*
         * This case can occur if new references were acquired while
         * we were blocked.
         */
        if (m->hold_count > 1) {
                KKASSERT(m->hold_count > 1);
                vm_page_unhold(m);
                return 0;
        }

        /*
         * Unmap the page table page
         */
        KKASSERT(m->hold_count == 1);
        vm_page_busy(m);
        pmap_inval_interlock(info, pmap, -1);

        if (m->pindex >= (NUPDE + NUPDPE)) {
                /* PDP page */
                pml4_entry_t *pml4;
                pml4 = pmap_pml4e(pmap, va);
                *pml4 = 0;
        } else if (m->pindex >= NUPDE) {
                /* PD page */
                pdp_entry_t *pdp;
                pdp = pmap_pdpe(pmap, va);
                *pdp = 0;
        } else {
                /* PT page */
                pd_entry_t *pd;
                pd = pmap_pde(pmap, va);
                *pd = 0;
        }

        KKASSERT(pmap->pm_stats.resident_count > 0);
        --pmap->pm_stats.resident_count;

        if (pmap->pm_ptphint == m)
                pmap->pm_ptphint = NULL;
        pmap_inval_deinterlock(info, pmap);

        if (m->pindex < NUPDE) {
                /* We just released a PT, unhold the matching PD */
                vm_page_t pdpg;

                pdpg = PHYS_TO_VM_PAGE(*pmap_pdpe(pmap, va) & PG_FRAME);
                pmap_unwire_pte_hold(pmap, va, pdpg, info);
        }
        if (m->pindex >= NUPDE && m->pindex < (NUPDE + NUPDPE)) {
                /* We just released a PD, unhold the matching PDP */
                vm_page_t pdppg;

                pdppg = PHYS_TO_VM_PAGE(*pmap_pml4e(pmap, va) & PG_FRAME);
                pmap_unwire_pte_hold(pmap, va, pdppg, info);
        }

        /*
         * This was our last hold, the page had better be unwired
         * after we decrement wire_count.
         *
         * FUTURE NOTE: shared page directory page could result in
         * multiple wire counts.
         */
        vm_page_unhold(m);
        --m->wire_count;
        KKASSERT(m->wire_count == 0);
        --vmstats.v_wire_count;
        vm_page_flag_clear(m, PG_MAPPED | PG_WRITEABLE);
        vm_page_flash(m);
        vm_page_free_zero(m);

        return 1;
}

/*
 * After removing a page table entry, this routine is used to
 * conditionally free the page, and manage the hold/wire counts.
 */
static
int
pmap_unuse_pt(pmap_t pmap, vm_offset_t va, vm_page_t mpte,
                pmap_inval_info_t info)
{
        vm_pindex_t ptepindex;

        if (va >= VM_MAX_USER_ADDRESS)
                return 0;

        if (mpte == NULL) {
                ptepindex = pmap_pde_pindex(va);
#if JGHINT
                if (pmap->pm_ptphint &&
                        (pmap->pm_ptphint->pindex == ptepindex)) {
                        mpte = pmap->pm_ptphint;
                } else {
#endif
                        pmap_inval_flush(info);
                        mpte = pmap_page_lookup(pmap->pm_pteobj, ptepindex);
                        pmap->pm_ptphint = mpte;
#if JGHINT
                }
#endif
        }
        return pmap_unwire_pte_hold(pmap, va, mpte, info);
}

/*
 * Initialize pmap0/vmspace0.  This pmap is not added to pmap_list because
 * it, and IdlePTD, represents the template used to update all other pmaps.
 *
 * On architectures where the kernel pmap is not integrated into the user
 * process pmap, this pmap represents the process pmap, not the kernel pmap.
 * kernel_pmap should be used to directly access the kernel_pmap.
 */
void
pmap_pinit0(struct pmap *pmap)
{
        pmap->pm_pml4 = (pml4_entry_t *)(PTOV_OFFSET + KPML4phys);
        pmap->pm_count = 1;
        pmap->pm_active = 0;
        pmap->pm_ptphint = NULL;
        TAILQ_INIT(&pmap->pm_pvlist);
        bzero(&pmap->pm_stats, sizeof pmap->pm_stats);
}

/*
 * Initialize a preallocated and zeroed pmap structure,
 * such as one in a vmspace structure.
 */
void
pmap_pinit(struct pmap *pmap)
{
        vm_page_t ptdpg;

        /*
         * No need to allocate page table space yet but we do need a valid
         * page directory table.
         */
        if (pmap->pm_pml4 == NULL) {
                pmap->pm_pml4 =
                    (pml4_entry_t *)kmem_alloc_pageable(&kernel_map, PAGE_SIZE);
        }

        /*
         * Allocate an object for the ptes
         */
        if (pmap->pm_pteobj == NULL)
                pmap->pm_pteobj = vm_object_allocate(OBJT_DEFAULT, NUPDE + NUPDPE + PML4PML4I + 1);

        /*
         * Allocate the page directory page, unless we already have
         * one cached.  If we used the cached page the wire_count will
         * already be set appropriately.
         */
        if ((ptdpg = pmap->pm_pdirm) == NULL) {
                ptdpg = vm_page_grab(pmap->pm_pteobj, NUPDE + NUPDPE + PML4PML4I,
                                     VM_ALLOC_NORMAL | VM_ALLOC_RETRY);
                pmap->pm_pdirm = ptdpg;
                vm_page_flag_clear(ptdpg, PG_MAPPED | PG_BUSY);
                ptdpg->valid = VM_PAGE_BITS_ALL;
                if (ptdpg->wire_count == 0)
                        ++vmstats.v_wire_count;
                ptdpg->wire_count = 1;
                pmap_kenter((vm_offset_t)pmap->pm_pml4, VM_PAGE_TO_PHYS(ptdpg));
        }
        if ((ptdpg->flags & PG_ZERO) == 0)
                bzero(pmap->pm_pml4, PAGE_SIZE);

        pmap->pm_pml4[KPML4I] = KPDPphys | PG_RW | PG_V | PG_U;
        pmap->pm_pml4[DMPML4I] = DMPDPphys | PG_RW | PG_V | PG_U;

        /* install self-referential address mapping entry */
        pmap->pm_pml4[PML4PML4I] = VM_PAGE_TO_PHYS(ptdpg) | PG_V | PG_RW | PG_A | PG_M;

        pmap->pm_count = 1;
        pmap->pm_active = 0;
        pmap->pm_ptphint = NULL;
        TAILQ_INIT(&pmap->pm_pvlist);
        bzero(&pmap->pm_stats, sizeof pmap->pm_stats);
        pmap->pm_stats.resident_count = 1;
}

/*
 * Clean up a pmap structure so it can be physically freed.  This routine
 * is called by the vmspace dtor function.  A great deal of pmap data is
 * left passively mapped to improve vmspace management so we have a bit
 * of cleanup work to do here.
 */
void
pmap_puninit(pmap_t pmap)
{
        vm_page_t p;

        KKASSERT(pmap->pm_active == 0);
        lwkt_gettoken(&vm_token);
        if ((p = pmap->pm_pdirm) != NULL) {
                KKASSERT(pmap->pm_pml4 != NULL);
                KKASSERT(pmap->pm_pml4 != (void *)(PTOV_OFFSET + KPML4phys));
                pmap_kremove((vm_offset_t)pmap->pm_pml4);
                p->wire_count--;
                vmstats.v_wire_count--;
                KKASSERT((p->flags & PG_BUSY) == 0);
                vm_page_busy(p);
                vm_page_free_zero(p);
                pmap->pm_pdirm = NULL;
        }
        if (pmap->pm_pml4) {
                KKASSERT(pmap->pm_pml4 != (void *)(PTOV_OFFSET + KPML4phys));
                kmem_free(&kernel_map, (vm_offset_t)pmap->pm_pml4, PAGE_SIZE);
                pmap->pm_pml4 = NULL;
        }
        if (pmap->pm_pteobj) {
                vm_object_deallocate(pmap->pm_pteobj);
                pmap->pm_pteobj = NULL;
        }
        lwkt_reltoken(&vm_token);
}

/*
 * Wire in kernel global address entries.  To avoid a race condition
 * between pmap initialization and pmap_growkernel, this procedure
 * adds the pmap to the master list (which growkernel scans to update),
 * then copies the template.
 */
void
pmap_pinit2(struct pmap *pmap)
{
        crit_enter();
        lwkt_gettoken(&vm_token);
        TAILQ_INSERT_TAIL(&pmap_list, pmap, pm_pmnode);
        /* XXX copies current process, does not fill in MPPTDI */
        lwkt_reltoken(&vm_token);
        crit_exit();
}

/*
 * Attempt to release and free a vm_page in a pmap.  Returns 1 on success,
 * 0 on failure (if the procedure had to sleep).
 *
 * When asked to remove the page directory page itself, we actually just
 * leave it cached so we do not have to incur the SMP inval overhead of
 * removing the kernel mapping.  pmap_puninit() will take care of it.
 */
static
int
pmap_release_free_page(struct pmap *pmap, vm_page_t p)
{
        /*
         * This code optimizes the case of freeing non-busy
         * page-table pages.  Those pages are zero now, and
         * might as well be placed directly into the zero queue.
         */
        if (vm_page_sleep_busy(p, FALSE, "pmaprl"))
                return 0;

        vm_page_busy(p);

        /*
         * Remove the page table page from the processes address space.
         */
        if (p->pindex == NUPDE + NUPDPE + PML4PML4I) {
                /*
                 * We are the pml4 table itself.
                 */
                /* XXX anything to do here? */
        } else if (p->pindex >= (NUPDE + NUPDPE)) {
                /*
                 * Remove a PDP page from the PML4.  We do not maintain
                 * hold counts on the PML4 page.
                 */
                pml4_entry_t *pml4;
                vm_page_t m4;
                int idx;

                m4 = vm_page_lookup(pmap->pm_pteobj, NUPDE + NUPDPE + PML4PML4I);
                KKASSERT(m4 != NULL);
                pml4 = (void *)PHYS_TO_DMAP(VM_PAGE_TO_PHYS(m4));
                idx = (p->pindex - (NUPDE + NUPDPE)) % NPML4EPG;
                KKASSERT(pml4[idx] != 0);
                pml4[idx] = 0;
        } else if (p->pindex >= NUPDE) {
                /*
                 * Remove a PD page from the PDP and drop the hold count
                 * on the PDP.  The PDP is left cached in the pmap if
                 * the hold count drops to 0 so the wire count remains
                 * intact.
                 */
                vm_page_t m3;
                pdp_entry_t *pdp;
                int idx;

                m3 = vm_page_lookup(pmap->pm_pteobj,
                                NUPDE + NUPDPE + (p->pindex - NUPDE) / NPDPEPG);
                KKASSERT(m3 != NULL);
                pdp = (void *)PHYS_TO_DMAP(VM_PAGE_TO_PHYS(m3));
                idx = (p->pindex - NUPDE) % NPDPEPG;
                KKASSERT(pdp[idx] != 0);
                pdp[idx] = 0;
                m3->hold_count--;
        } else {
                /*
                 * Remove a PT page from the PD and drop the hold count
                 * on the PD.  The PD is left cached in the pmap if
                 * the hold count drops to 0 so the wire count remains
                 * intact.
                 */
                vm_page_t m2;
                pd_entry_t *pd;
                int idx;

                m2 = vm_page_lookup(pmap->pm_pteobj,
                                    NUPDE + p->pindex / NPDEPG);
                KKASSERT(m2 != NULL);
                pd = (void *)PHYS_TO_DMAP(VM_PAGE_TO_PHYS(m2));
                idx = p->pindex % NPDEPG;
                pd[idx] = 0;
                m2->hold_count--;
        }

        /*
         * One fewer mappings in the pmap.  p's hold count had better
         * be zero.
         */
        KKASSERT(pmap->pm_stats.resident_count > 0);
        --pmap->pm_stats.resident_count;
        if (p->hold_count)
                panic("pmap_release: freeing held page table page");
        if (pmap->pm_ptphint && (pmap->pm_ptphint->pindex == p->pindex))
                pmap->pm_ptphint = NULL;

        /*
         * We leave the top-level page table page cached, wired, and mapped in
         * the pmap until the dtor function (pmap_puninit()) gets called.
         * However, still clean it up so we can set PG_ZERO.
         */
        if (p->pindex == NUPDE + NUPDPE + PML4PML4I) {
                bzero(pmap->pm_pml4, PAGE_SIZE);
                vm_page_flag_set(p, PG_ZERO);
                vm_page_wakeup(p);
        } else {
                p->wire_count--;
                KKASSERT(p->wire_count == 0);
                vmstats.v_wire_count--;
                /* JG eventually revert to using vm_page_free_zero() */
                vm_page_free(p);
        }
        return 1;
}

/*
 * This routine is called when various levels in the page table need to
 * be populated.  This routine cannot fail.
 */
static
vm_page_t
_pmap_allocpte(pmap_t pmap, vm_pindex_t ptepindex)
{
        vm_page_t m;

        /*
         * Find or fabricate a new pagetable page.  This will busy the page.
         */
        m = vm_page_grab(pmap->pm_pteobj, ptepindex,
                         VM_ALLOC_NORMAL | VM_ALLOC_ZERO | VM_ALLOC_RETRY);
        if ((m->flags & PG_ZERO) == 0) {
                pmap_zero_page(VM_PAGE_TO_PHYS(m));
        }

        KASSERT(m->queue == PQ_NONE,
                ("_pmap_allocpte: %p->queue != PQ_NONE", m));

        /*
         * Increment the hold count for the page we will be returning to
         * the caller.
         */
        m->hold_count++;
        if (m->wire_count++ == 0)
                vmstats.v_wire_count++;

        /*
         * Map the pagetable page into the process address space, if
         * it isn't already there.
         *
         * It is possible that someone else got in and mapped the page
         * directory page while we were blocked, if so just unbusy and
         * return the held page.
         */
        if (ptepindex >= (NUPDE + NUPDPE)) {
                /*
                 * Wire up a new PDP page in the PML4
                 */
                vm_pindex_t pml4index;
                pml4_entry_t *pml4;

                pml4index = ptepindex - (NUPDE + NUPDPE);
                pml4 = &pmap->pm_pml4[pml4index];
                if (*pml4 & PG_V) {
                        if (--m->wire_count == 0)
                                --vmstats.v_wire_count;
                        vm_page_wakeup(m);
                        return(m);
                }
                *pml4 = VM_PAGE_TO_PHYS(m) | PG_U | PG_RW | PG_V | PG_A | PG_M;
        } else if (ptepindex >= NUPDE) {
                /*
                 * Wire up a new PD page in the PDP
                 */
                vm_pindex_t pml4index;
                vm_pindex_t pdpindex;
                vm_page_t pdppg;
                pml4_entry_t *pml4;
                pdp_entry_t *pdp;

                pdpindex = ptepindex - NUPDE;
                pml4index = pdpindex >> NPML4EPGSHIFT;

                pml4 = &pmap->pm_pml4[pml4index];
                if ((*pml4 & PG_V) == 0) {
                        /*
                         * Have to allocate a new PDP page, recurse.
                         * This always succeeds.  Returned page will
                         * be held.
                         */
                        pdppg = _pmap_allocpte(pmap,
                                               NUPDE + NUPDPE + pml4index);
                } else {
                        /*
                         * Add a held reference to the PDP page.
                         */
                        pdppg = PHYS_TO_VM_PAGE(*pml4 & PG_FRAME);
                        pdppg->hold_count++;
                }

                /*
                 * Now find the pdp_entry and map the PDP.  If the PDP
                 * has already been mapped unwind and return the
                 * already-mapped PDP held.
                 *
                 * pdppg is left held (hold_count is incremented for
                 * each PD in the PDP).
                 */
                pdp = (pdp_entry_t *)PHYS_TO_DMAP(*pml4 & PG_FRAME);
                pdp = &pdp[pdpindex & ((1ul << NPDPEPGSHIFT) - 1)];
                if (*pdp & PG_V) {
                        vm_page_unhold(pdppg);
                        if (--m->wire_count == 0)
                                --vmstats.v_wire_count;
                        vm_page_wakeup(m);
                        return(m);
                }
                *pdp = VM_PAGE_TO_PHYS(m) | PG_U | PG_RW | PG_V | PG_A | PG_M;
        } else {
                /*
                 * Wire up the new PT page in the PD
                 */
                vm_pindex_t pml4index;
                vm_pindex_t pdpindex;
                pml4_entry_t *pml4;
                pdp_entry_t *pdp;
                pd_entry_t *pd;
                vm_page_t pdpg;

                pdpindex = ptepindex >> NPDPEPGSHIFT;
                pml4index = pdpindex >> NPML4EPGSHIFT;

                /*
                 * Locate the PDP page in the PML4, then the PD page in
                 * the PDP.  If either does not exist we simply recurse
                 * to allocate them.
                 *
                 * We can just recurse on the PD page as it will recurse
                 * on the PDP if necessary.
                 */
                pml4 = &pmap->pm_pml4[pml4index];
                if ((*pml4 & PG_V) == 0) {
                        pdpg = _pmap_allocpte(pmap, NUPDE + pdpindex);
                        pdp = (pdp_entry_t *)PHYS_TO_DMAP(*pml4 & PG_FRAME);
                        pdp = &pdp[pdpindex & ((1ul << NPDPEPGSHIFT) - 1)];
                } else {
                        pdp = (pdp_entry_t *)PHYS_TO_DMAP(*pml4 & PG_FRAME);
                        pdp = &pdp[pdpindex & ((1ul << NPDPEPGSHIFT) - 1)];
                        if ((*pdp & PG_V) == 0) {
                                pdpg = _pmap_allocpte(pmap, NUPDE + pdpindex);
                        } else {
                                pdpg = PHYS_TO_VM_PAGE(*pdp & PG_FRAME);
                                pdpg->hold_count++;
                        }
                }

                /*
                 * Now fill in the pte in the PD.  If the pte already exists
                 * (again, if we raced the grab), unhold pdpg and unwire
                 * m, returning a held m.
                 *
                 * pdpg is left held (hold_count is incremented for
                 * each PT in the PD).
                 */
                pd = (pd_entry_t *)PHYS_TO_DMAP(*pdp & PG_FRAME);
                pd = &pd[ptepindex & ((1ul << NPDEPGSHIFT) - 1)];
                if (*pd != 0) {
                        vm_page_unhold(pdpg);
                        if (--m->wire_count == 0)
                                --vmstats.v_wire_count;
                        vm_page_wakeup(m);
                        return(m);
                }
                *pd = VM_PAGE_TO_PHYS(m) | PG_U | PG_RW | PG_V | PG_A | PG_M;
        }

        /*
         * We successfully loaded a PDP, PD, or PTE.  Set the page table hint,
         * valid bits, mapped flag, unbusy, and we're done.
         */
        pmap->pm_ptphint = m;
        ++pmap->pm_stats.resident_count;

        m->valid = VM_PAGE_BITS_ALL;
        vm_page_flag_clear(m, PG_ZERO);
        vm_page_flag_set(m, PG_MAPPED);
        vm_page_wakeup(m);

        return (m);
}

static
vm_page_t
pmap_allocpte(pmap_t pmap, vm_offset_t va)
{
        vm_pindex_t ptepindex;
        pd_entry_t *pd;
        vm_page_t m;

        /*
         * Calculate pagetable page index
         */
        ptepindex = pmap_pde_pindex(va);

        /*
         * Get the page directory entry
         */
        pd = pmap_pde(pmap, va);

        /*
         * This supports switching from a 2MB page to a
         * normal 4K page.
         */
        if (pd != NULL && (*pd & (PG_PS | PG_V)) == (PG_PS | PG_V)) {
                panic("no promotion/demotion yet");
                *pd = 0;
                pd = NULL;
                cpu_invltlb();
                smp_invltlb();
        }

        /*
         * If the page table page is mapped, we just increment the
         * hold count, and activate it.
         */
        if (pd != NULL && (*pd & PG_V) != 0) {
                /* YYY hint is used here on i386 */
                m = pmap_page_lookup( pmap->pm_pteobj, ptepindex);
                pmap->pm_ptphint = m;
                m->hold_count++;
                return m;
        }
        /*
         * Here if the pte page isn't mapped, or if it has been deallocated.
         */
        return _pmap_allocpte(pmap, ptepindex);
}


/***************************************************
 * Pmap allocation/deallocation routines.
 ***************************************************/

/*
 * Release any resources held by the given physical map.
 * Called when a pmap initialized by pmap_pinit is being released.
 * Should only be called if the map contains no valid mappings.
 */
static int pmap_release_callback(struct vm_page *p, void *data);

void
pmap_release(struct pmap *pmap)
{
        vm_object_t object = pmap->pm_pteobj;
        struct rb_vm_page_scan_info info;

        KASSERT(pmap->pm_active == 0, ("pmap still active! %08x", pmap->pm_active));
#if defined(DIAGNOSTIC)
        if (object->ref_count != 1)
                panic("pmap_release: pteobj reference count != 1");
#endif
        
        info.pmap = pmap;
        info.object = object;
        crit_enter();
        lwkt_gettoken(&vm_token);
        TAILQ_REMOVE(&pmap_list, pmap, pm_pmnode);
        crit_exit();

        do {
                crit_enter();
                info.error = 0;
                info.mpte = NULL;
                info.limit = object->generation;

                vm_page_rb_tree_RB_SCAN(&object->rb_memq, NULL, 
                                        pmap_release_callback, &info);
                if (info.error == 0 && info.mpte) {
                        if (!pmap_release_free_page(pmap, info.mpte))
                                info.error = 1;
                }
                crit_exit();
        } while (info.error);
        lwkt_reltoken(&vm_token);
}

static
int
pmap_release_callback(struct vm_page *p, void *data)
{
        struct rb_vm_page_scan_info *info = data;

        if (p->pindex == NUPDE + NUPDPE + PML4PML4I) {
                info->mpte = p;
                return(0);
        }
        if (!pmap_release_free_page(info->pmap, p)) {
                info->error = 1;
                return(-1);
        }
        if (info->object->generation != info->limit) {
                info->error = 1;
                return(-1);
        }
        return(0);
}

/*
 * Grow the number of kernel page table entries, if needed.
 *
 * This routine is always called to validate any address space
 * beyond KERNBASE (for kldloads).  kernel_vm_end only governs the address
 * space below KERNBASE.
 */
void
pmap_growkernel(vm_offset_t kstart, vm_offset_t kend)
{
        vm_paddr_t paddr;
        vm_offset_t ptppaddr;
        vm_page_t nkpg;
        pd_entry_t *pde, newpdir;
        pdp_entry_t newpdp;
        int update_kernel_vm_end;

        crit_enter();
        lwkt_gettoken(&vm_token);

        /*
         * bootstrap kernel_vm_end on first real VM use
         */
        if (kernel_vm_end == 0) {
                kernel_vm_end = VM_MIN_KERNEL_ADDRESS;
                nkpt = 0;
                while ((*pmap_pde(&kernel_pmap, kernel_vm_end) & PG_V) != 0) {
                        kernel_vm_end = (kernel_vm_end + PAGE_SIZE * NPTEPG) &
                                        ~(PAGE_SIZE * NPTEPG - 1);
                        nkpt++;
                        if (kernel_vm_end - 1 >= kernel_map.max_offset) {
                                kernel_vm_end = kernel_map.max_offset;
                                break;                       
                        }
                }
        }

        /*
         * Fill in the gaps.  kernel_vm_end is only adjusted for ranges
         * below KERNBASE.  Ranges above KERNBASE are kldloaded and we
         * do not want to force-fill 128G worth of page tables.
         */
        if (kstart < KERNBASE) {
                if (kstart > kernel_vm_end)
                        kstart = kernel_vm_end;
                KKASSERT(kend <= KERNBASE);
                update_kernel_vm_end = 1;
        } else {
                update_kernel_vm_end = 0;
        }

        kstart = rounddown2(kstart, PAGE_SIZE * NPTEPG);
        kend = roundup2(kend, PAGE_SIZE * NPTEPG);

        if (kend - 1 >= kernel_map.max_offset)
                kend = kernel_map.max_offset;

        while (kstart < kend) {
                pde = pmap_pde(&kernel_pmap, kstart);
                if (pde == NULL) {
                        /* We need a new PDP entry */
                        nkpg = vm_page_alloc(kptobj, nkpt,
                                             VM_ALLOC_NORMAL |
                                             VM_ALLOC_SYSTEM |
                                             VM_ALLOC_INTERRUPT);
                        if (nkpg == NULL) {
                                panic("pmap_growkernel: no memory to grow "
                                      "kernel");
                        }
                        paddr = VM_PAGE_TO_PHYS(nkpg);
                        if ((nkpg->flags & PG_ZERO) == 0)
                                pmap_zero_page(paddr);
                        vm_page_flag_clear(nkpg, PG_ZERO);
                        newpdp = (pdp_entry_t)
                                (paddr | PG_V | PG_RW | PG_A | PG_M);
                        *pmap_pdpe(&kernel_pmap, kstart) = newpdp;
                        nkpt++;
                        continue; /* try again */
                }
                if ((*pde & PG_V) != 0) {
                        kstart = (kstart + PAGE_SIZE * NPTEPG) &
                                 ~(PAGE_SIZE * NPTEPG - 1);
                        if (kstart - 1 >= kernel_map.max_offset) {
                                kstart = kernel_map.max_offset;
                                break;                       
                        }
                        continue;
                }

                /*
                 * This index is bogus, but out of the way
                 */
                nkpg = vm_page_alloc(kptobj, nkpt,
                                     VM_ALLOC_NORMAL |
                                     VM_ALLOC_SYSTEM |
                                     VM_ALLOC_INTERRUPT);
                if (nkpg == NULL)
                        panic("pmap_growkernel: no memory to grow kernel");

                vm_page_wire(nkpg);
                ptppaddr = VM_PAGE_TO_PHYS(nkpg);
                pmap_zero_page(ptppaddr);
                vm_page_flag_clear(nkpg, PG_ZERO);
                newpdir = (pd_entry_t) (ptppaddr | PG_V | PG_RW | PG_A | PG_M);
                *pmap_pde(&kernel_pmap, kstart) = newpdir;
                nkpt++;

                kstart = (kstart + PAGE_SIZE * NPTEPG) &
                          ~(PAGE_SIZE * NPTEPG - 1);

                if (kstart - 1 >= kernel_map.max_offset) {
                        kstart = kernel_map.max_offset;
                        break;                       
                }
        }

        /*
         * Only update kernel_vm_end for areas below KERNBASE.
         */
        if (update_kernel_vm_end && kernel_vm_end < kstart)
                kernel_vm_end = kstart;

        lwkt_reltoken(&vm_token);
        crit_exit();
}

/*
 *      Retire the given physical map from service.
 *      Should only be called if the map contains
 *      no valid mappings.
 */
void
pmap_destroy(pmap_t pmap)
{
        int count;

        if (pmap == NULL)
                return;

        lwkt_gettoken(&vm_token);
        count = --pmap->pm_count;
        if (count == 0) {
                pmap_release(pmap);
                panic("destroying a pmap is not yet implemented");
        }
        lwkt_reltoken(&vm_token);
}

/*
 *      Add a reference to the specified pmap.
 */
void
pmap_reference(pmap_t pmap)
{
        if (pmap != NULL) {
                lwkt_gettoken(&vm_token);
                pmap->pm_count++;
                lwkt_reltoken(&vm_token);
        }
}

/***************************************************
* page management routines.
 ***************************************************/

/*
 * free the pv_entry back to the free list.  This function may be
 * called from an interrupt.
 */
static __inline
void
free_pv_entry(pv_entry_t pv)
{
        pv_entry_count--;
        KKASSERT(pv_entry_count >= 0);
        zfree(pvzone, pv);
}

/*
 * get a new pv_entry, allocating a block from the system
 * when needed.  This function may be called from an interrupt.
 */
static
pv_entry_t
get_pv_entry(void)
{
        pv_entry_count++;
        if (pv_entry_high_water &&
                (pv_entry_count > pv_entry_high_water) &&
                (pmap_pagedaemon_waken == 0)) {
                pmap_pagedaemon_waken = 1;
                wakeup(&vm_pages_needed);
        }
        return zalloc(pvzone);
}

/*
 * This routine is very drastic, but can save the system
 * in a pinch.
 */
void
pmap_collect(void)
{
        int i;
        vm_page_t m;
        static int warningdone=0;

        if (pmap_pagedaemon_waken == 0)
                return;
        lwkt_gettoken(&vm_token);
        if (warningdone < 5) {
                kprintf("pmap_collect: collecting pv entries -- suggest increasing PMAP_SHPGPERPROC\n");
                warningdone++;
        }

        for(i = 0; i < vm_page_array_size; i++) {
                m = &vm_page_array[i];
                if (m->wire_count || m->hold_count || m->busy ||
                    (m->flags & PG_BUSY))
                        continue;
                pmap_remove_all(m);
        }
        pmap_pagedaemon_waken = 0;
        lwkt_reltoken(&vm_token);
}
        

/*
 * If it is the first entry on the list, it is actually
 * in the header and we must copy the following entry up
 * to the header.  Otherwise we must search the list for
 * the entry.  In either case we free the now unused entry.
 */
static
int
pmap_remove_entry(struct pmap *pmap, vm_page_t m, 
                        vm_offset_t va, pmap_inval_info_t info)
{
        pv_entry_t pv;
        int rtval;

        crit_enter();
        if (m->md.pv_list_count < pmap->pm_stats.resident_count) {
                TAILQ_FOREACH(pv, &m->md.pv_list, pv_list) {
                        if (pmap == pv->pv_pmap && va == pv->pv_va) 
                                break;
                }
        } else {
                TAILQ_FOREACH(pv, &pmap->pm_pvlist, pv_plist) {
                        if (va == pv->pv_va) 
                                break;
                }
        }

        rtval = 0;
        KKASSERT(pv);

        TAILQ_REMOVE(&m->md.pv_list, pv, pv_list);
        m->md.pv_list_count--;
        KKASSERT(m->md.pv_list_count >= 0);
        if (TAILQ_EMPTY(&m->md.pv_list))
                vm_page_flag_clear(m, PG_MAPPED | PG_WRITEABLE);
        TAILQ_REMOVE(&pmap->pm_pvlist, pv, pv_plist);
        ++pmap->pm_generation;
        rtval = pmap_unuse_pt(pmap, va, pv->pv_ptem, info);
        free_pv_entry(pv);

        crit_exit();
        return rtval;
}

/*
 * Create a pv entry for page at pa for
 * (pmap, va).
 */
static
void
pmap_insert_entry(pmap_t pmap, vm_offset_t va, vm_page_t mpte, vm_page_t m)
{
        pv_entry_t pv;

        crit_enter();
        pv = get_pv_entry();
        pv->pv_va = va;
        pv->pv_pmap = pmap;
        pv->pv_ptem = mpte;

        TAILQ_INSERT_TAIL(&pmap->pm_pvlist, pv, pv_plist);
        TAILQ_INSERT_TAIL(&m->md.pv_list, pv, pv_list);
        ++pmap->pm_generation;
        m->md.pv_list_count++;

        crit_exit();
}

/*
 * pmap_remove_pte: do the things to unmap a page in a process
 */
static
int
pmap_remove_pte(struct pmap *pmap, pt_entry_t *ptq, vm_offset_t va,
        pmap_inval_info_t info)
{
        pt_entry_t oldpte;
        vm_page_t m;

        pmap_inval_interlock(info, pmap, va);
        oldpte = pte_load_clear(ptq);
        pmap_inval_deinterlock(info, pmap);
        if (oldpte & PG_W)
                pmap->pm_stats.wired_count -= 1;
        /*
         * Machines that don't support invlpg, also don't support
         * PG_G.  XXX PG_G is disabled for SMP so don't worry about
         * the SMP case.
         */
        if (oldpte & PG_G)
                cpu_invlpg((void *)va);
        KKASSERT(pmap->pm_stats.resident_count > 0);
        --pmap->pm_stats.resident_count;
        if (oldpte & PG_MANAGED) {
                m = PHYS_TO_VM_PAGE(oldpte);
                if (oldpte & PG_M) {
#if defined(PMAP_DIAGNOSTIC)
                        if (pmap_nw_modified((pt_entry_t) oldpte)) {
                                kprintf(
        "pmap_remove: modified page not writable: va: 0x%lx, pte: 0x%lx\n",
                                    va, oldpte);
                        }
#endif
                        if (pmap_track_modified(va))
                                vm_page_dirty(m);
                }
                if (oldpte & PG_A)
                        vm_page_flag_set(m, PG_REFERENCED);
                return pmap_remove_entry(pmap, m, va, info);
        } else {
                return pmap_unuse_pt(pmap, va, NULL, info);
        }

        return 0;
}

/*
 * pmap_remove_page:
 *
 *      Remove a single page from a process address space.
 *
 *      This function may not be called from an interrupt if the pmap is
 *      not kernel_pmap.
 */
static
void
pmap_remove_page(struct pmap *pmap, vm_offset_t va, pmap_inval_info_t info)
{
        pt_entry_t *pte;

        pte = pmap_pte(pmap, va);
        if (pte == NULL)
                return;
        if ((*pte & PG_V) == 0)
                return;
        pmap_remove_pte(pmap, pte, va, info);
}

/*
 * pmap_remove:
 *
 *      Remove the given range of addresses from the specified map.
 *
 *      It is assumed that the start and end are properly
 *      rounded to the page size.
 *
 *      This function may not be called from an interrupt if the pmap is
 *      not kernel_pmap.
 */
void
pmap_remove(struct pmap *pmap, vm_offset_t sva, vm_offset_t eva)
{
        vm_offset_t va_next;
        pml4_entry_t *pml4e;
        pdp_entry_t *pdpe;
        pd_entry_t ptpaddr, *pde;
        pt_entry_t *pte;
        struct pmap_inval_info info;

        if (pmap == NULL)
                return;

        lwkt_gettoken(&vm_token);
        if (pmap->pm_stats.resident_count == 0) {
                lwkt_reltoken(&vm_token);
                return;
        }

        pmap_inval_init(&info);

        /*
         * special handling of removing one page.  a very
         * common operation and easy to short circuit some
         * code.
         */
        if (sva + PAGE_SIZE == eva) {
                pde = pmap_pde(pmap, sva);
                if (pde && (*pde & PG_PS) == 0) {
                        pmap_remove_page(pmap, sva, &info);
                        pmap_inval_done(&info);
                        lwkt_reltoken(&vm_token);
                        return;
                }
        }

        for (; sva < eva; sva = va_next) {
                pml4e = pmap_pml4e(pmap, sva);
                if ((*pml4e & PG_V) == 0) {
                        va_next = (sva + NBPML4) & ~PML4MASK;
                        if (va_next < sva)
                                va_next = eva;
                        continue;
                }

                pdpe = pmap_pml4e_to_pdpe(pml4e, sva);
                if ((*pdpe & PG_V) == 0) {
                        va_next = (sva + NBPDP) & ~PDPMASK;
                        if (va_next < sva)
                                va_next = eva;
                        continue;
                }

                /*
                 * Calculate index for next page table.
                 */
                va_next = (sva + NBPDR) & ~PDRMASK;
                if (va_next < sva)
                        va_next = eva;

                pde = pmap_pdpe_to_pde(pdpe, sva);
                ptpaddr = *pde;

                /*
                 * Weed out invalid mappings.
                 */
                if (ptpaddr == 0)
                        continue;

                /*
                 * Check for large page.
                 */
                if ((ptpaddr & PG_PS) != 0) {
                        /* JG FreeBSD has more complex treatment here */
                        pmap_inval_interlock(&info, pmap, -1);
                        *pde = 0;
                        pmap->pm_stats.resident_count -= NBPDR / PAGE_SIZE;
                        pmap_inval_deinterlock(&info, pmap);
                        continue;
                }

                /*
                 * Limit our scan to either the end of the va represented
                 * by the current page table page, or to the end of the
                 * range being removed.
                 */
                if (va_next > eva)
                        va_next = eva;

                /*
                 * NOTE: pmap_remove_pte() can block.
                 */
                for (pte = pmap_pde_to_pte(pde, sva); sva != va_next; pte++,
                    sva += PAGE_SIZE) {
                        if (*pte == 0)
                                continue;
                        if (pmap_remove_pte(pmap, pte, sva, &info))
                                break;
                }
        }
        pmap_inval_done(&info);
        lwkt_reltoken(&vm_token);
}

/*
 * pmap_remove_all:
 *
 *      Removes this physical page from all physical maps in which it resides.
 *      Reflects back modify bits to the pager.
 *
 *      This routine may not be called from an interrupt.
 */

static
void
pmap_remove_all(vm_page_t m)
{
        struct pmap_inval_info info;
        pt_entry_t *pte, tpte;
        pv_entry_t pv;

        if (!pmap_initialized || (m->flags & PG_FICTITIOUS))
                return;

        lwkt_gettoken(&vm_token);
        pmap_inval_init(&info);
        crit_enter();
        while ((pv = TAILQ_FIRST(&m->md.pv_list)) != NULL) {
                KKASSERT(pv->pv_pmap->pm_stats.resident_count > 0);
                --pv->pv_pmap->pm_stats.resident_count;

                pte = pmap_pte_quick(pv->pv_pmap, pv->pv_va);
                pmap_inval_interlock(&info, pv->pv_pmap, pv->pv_va);
                tpte = pte_load_clear(pte);
                if (tpte & PG_W)
                        pv->pv_pmap->pm_stats.wired_count--;
                pmap_inval_deinterlock(&info, pv->pv_pmap);
                if (tpte & PG_A)
                        vm_page_flag_set(m, PG_REFERENCED);

                /*
                 * Update the vm_page_t clean and reference bits.
                 */
                if (tpte & PG_M) {
#if defined(PMAP_DIAGNOSTIC)
                        if (pmap_nw_modified(tpte)) {
                                kprintf(
        "pmap_remove_all: modified page not writable: va: 0x%lx, pte: 0x%lx\n",
                                    pv->pv_va, tpte);
                        }
#endif
                        if (pmap_track_modified(pv->pv_va))
                                vm_page_dirty(m);
                }
                TAILQ_REMOVE(&m->md.pv_list, pv, pv_list);
                TAILQ_REMOVE(&pv->pv_pmap->pm_pvlist, pv, pv_plist);
                ++pv->pv_pmap->pm_generation;
                m->md.pv_list_count--;
                KKASSERT(m->md.pv_list_count >= 0);
                if (TAILQ_EMPTY(&m->md.pv_list))
                        vm_page_flag_clear(m, PG_MAPPED | PG_WRITEABLE);
                pmap_unuse_pt(pv->pv_pmap, pv->pv_va, pv->pv_ptem, &info);
                free_pv_entry(pv);
        }
        crit_exit();
        KKASSERT((m->flags & (PG_MAPPED|PG_WRITEABLE)) == 0);
        pmap_inval_done(&info);
        lwkt_reltoken(&vm_token);
}

/*
 * pmap_protect:
 *
 *      Set the physical protection on the specified range of this map
 *      as requested.
 *
 *      This function may not be called from an interrupt if the map is
 *      not the kernel_pmap.
 */
void
pmap_protect(pmap_t pmap, vm_offset_t sva, vm_offset_t eva, vm_prot_t prot)
{
        vm_offset_t va_next;
        pml4_entry_t *pml4e;
        pdp_entry_t *pdpe;
        pd_entry_t ptpaddr, *pde;
        pt_entry_t *pte;
        pmap_inval_info info;

        /* JG review for NX */

        if (pmap == NULL)
                return;

        if ((prot & VM_PROT_READ) == VM_PROT_NONE) {
                pmap_remove(pmap, sva, eva);
                return;
        }

        if (prot & VM_PROT_WRITE)
                return;

        lwkt_gettoken(&vm_token);
        pmap_inval_init(&info);

        for (; sva < eva; sva = va_next) {

                pml4e = pmap_pml4e(pmap, sva);
                if ((*pml4e & PG_V) == 0) {
                        va_next = (sva + NBPML4) & ~PML4MASK;
                        if (va_next < sva)
                                va_next = eva;
                        continue;
                }

                pdpe = pmap_pml4e_to_pdpe(pml4e, sva);
                if ((*pdpe & PG_V) == 0) {
                        va_next = (sva + NBPDP) & ~PDPMASK;
                        if (va_next < sva)
                                va_next = eva;
                        continue;
                }

                va_next = (sva + NBPDR) & ~PDRMASK;
                if (va_next < sva)
                        va_next = eva;

                pde = pmap_pdpe_to_pde(pdpe, sva);
                ptpaddr = *pde;

                /*
                 * Check for large page.
                 */
                if ((ptpaddr & PG_PS) != 0) {
                        pmap_inval_interlock(&info, pmap, -1);
                        *pde &= ~(PG_M|PG_RW);
                        pmap->pm_stats.resident_count -= NBPDR / PAGE_SIZE;
                        pmap_inval_deinterlock(&info, pmap);
                        continue;
                }

                /*
                 * Weed out invalid mappings. Note: we assume that the page
                 * directory table is always allocated, and in kernel virtual.
                 */
                if (ptpaddr == 0)
                        continue;

                if (va_next > eva)
                        va_next = eva;

                for (pte = pmap_pde_to_pte(pde, sva); sva != va_next; pte++,
                     sva += PAGE_SIZE) {
                        pt_entry_t pbits;
                        pt_entry_t cbits;
                        vm_page_t m;

                        /*
                         * XXX non-optimal.  Note also that there can be
                         * no pmap_inval_flush() calls until after we modify
                         * ptbase[sindex] (or otherwise we have to do another
                         * pmap_inval_add() call).
                         */
                        pmap_inval_interlock(&info, pmap, sva);
again:
                        pbits = *pte;
                        cbits = pbits;
                        if ((pbits & PG_V) == 0) {
                                pmap_inval_deinterlock(&info, pmap);
                                continue;
                        }
                        if (pbits & PG_MANAGED) {
                                m = NULL;
                                if (pbits & PG_A) {
                                        m = PHYS_TO_VM_PAGE(pbits & PG_FRAME);
                                        vm_page_flag_set(m, PG_REFERENCED);
                                        cbits &= ~PG_A;
                                }
                                if (pbits & PG_M) {
                                        if (pmap_track_modified(sva)) {
                                                if (m == NULL)
                                                        m = PHYS_TO_VM_PAGE(pbits & PG_FRAME);
                                                vm_page_dirty(m);
                                                cbits &= ~PG_M;
                                        }
                                }
                        }
                        cbits &= ~PG_RW;
                        if (pbits != cbits &&
                            !atomic_cmpset_long(pte, pbits, cbits)) {
                                goto again;
                        }
                        pmap_inval_deinterlock(&info, pmap);
                }
        }
        pmap_inval_done(&info);
        lwkt_reltoken(&vm_token);
}

/*
 *      Insert the given physical page (p) at
 *      the specified virtual address (v) in the
 *      target physical map with the protection requested.
 *
 *      If specified, the page will be wired down, meaning
 *      that the related pte can not be reclaimed.
 *
 *      NB:  This is the only routine which MAY NOT lazy-evaluate
 *      or lose information.  That is, this routine must actually
 *      insert this page into the given map NOW.
 */
void
pmap_enter(pmap_t pmap, vm_offset_t va, vm_page_t m, vm_prot_t prot,
           boolean_t wired)
{
        vm_paddr_t pa;
        pd_entry_t *pde;
        pt_entry_t *pte;
        vm_paddr_t opa;
        pt_entry_t origpte, newpte;
        vm_page_t mpte;
        pmap_inval_info info;

        if (pmap == NULL)
                return;

        va = trunc_page(va);
#ifdef PMAP_DIAGNOSTIC
        if (va >= KvaEnd)
                panic("pmap_enter: toobig");
        if ((va >= UPT_MIN_ADDRESS) && (va < UPT_MAX_ADDRESS))
                panic("pmap_enter: invalid to pmap_enter page table pages (va: 0x%lx)", va);
#endif
        if (va < UPT_MAX_ADDRESS && pmap == &kernel_pmap) {
                kprintf("Warning: pmap_enter called on UVA with kernel_pmap\n");
#ifdef DDB
                db_print_backtrace();
#endif
        }
        if (va >= UPT_MAX_ADDRESS && pmap != &kernel_pmap) {
                kprintf("Warning: pmap_enter called on KVA without kernel_pmap\n");
#ifdef DDB
                db_print_backtrace();
#endif
        }

        lwkt_gettoken(&vm_token);

        /*
         * In the case that a page table page is not
         * resident, we are creating it here.
         */
        if (va < VM_MAX_USER_ADDRESS)
                mpte = pmap_allocpte(pmap, va);
        else
                mpte = NULL;

        pmap_inval_init(&info);
        pde = pmap_pde(pmap, va);
        if (pde != NULL && (*pde & PG_V) != 0) {
                if ((*pde & PG_PS) != 0)
                        panic("pmap_enter: attempted pmap_enter on 2MB page");
                pte = pmap_pde_to_pte(pde, va);
        } else
                panic("pmap_enter: invalid page directory va=%#lx", va);

        KKASSERT(pte != NULL);
        pa = VM_PAGE_TO_PHYS(m);
        origpte = *pte;
        opa = origpte & PG_FRAME;

        /*
         * Mapping has not changed, must be protection or wiring change.
         */
        if (origpte && (opa == pa)) {
                /*
                 * Wiring change, just update stats. We don't worry about
                 * wiring PT pages as they remain resident as long as there
                 * are valid mappings in them. Hence, if a user page is wired,
                 * the PT page will be also.
                 */
                if (wired && ((origpte & PG_W) == 0))
                        pmap->pm_stats.wired_count++;
                else if (!wired && (origpte & PG_W))
                        pmap->pm_stats.wired_count--;

#if defined(PMAP_DIAGNOSTIC)
                if (pmap_nw_modified(origpte)) {
                        kprintf(
        "pmap_enter: modified page not writable: va: 0x%lx, pte: 0x%lx\n",
                            va, origpte);
                }
#endif

                /*
                 * Remove the extra pte reference.  Note that we cannot
                 * optimize the RO->RW case because we have adjusted the
                 * wiring count above and may need to adjust the wiring
                 * bits below.
                 */
                if (mpte)
                        mpte->hold_count--;

                /*
                 * We might be turning off write access to the page,
                 * so we go ahead and sense modify status.
                 */
                if (origpte & PG_MANAGED) {
                        if ((origpte & PG_M) && pmap_track_modified(va)) {
                                vm_page_t om;
                                om = PHYS_TO_VM_PAGE(opa);
                                vm_page_dirty(om);
                        }
                        pa |= PG_MANAGED;
                        KKASSERT(m->flags & PG_MAPPED);
                }
                goto validate;
        } 
        /*
         * Mapping has changed, invalidate old range and fall through to
         * handle validating new mapping.
         */
        while (opa) {
                int err;
                err = pmap_remove_pte(pmap, pte, va, &info);
                if (err)
                        panic("pmap_enter: pte vanished, va: 0x%lx", va);
                origpte = *pte;
                opa = origpte & PG_FRAME;
                if (opa) {
                        kprintf("pmap_enter: Warning, raced pmap %p va %p\n",
                                pmap, (void *)va);
                }
        }

        /*
         * Enter on the PV list if part of our managed memory. Note that we
         * raise IPL while manipulating pv_table since pmap_enter can be
         * called at interrupt time.
         */
        if (pmap_initialized && 
            (m->flags & (PG_FICTITIOUS|PG_UNMANAGED)) == 0) {
                pmap_insert_entry(pmap, va, mpte, m);
                pa |= PG_MANAGED;
                vm_page_flag_set(m, PG_MAPPED);
        }

        /*
         * Increment counters
         */
        ++pmap->pm_stats.resident_count;
        if (wired)
                pmap->pm_stats.wired_count++;

validate:
        /*
         * Now validate mapping with desired protection/wiring.
         */
        newpte = (pt_entry_t) (pa | pte_prot(pmap, prot) | PG_V);

        if (wired)
                newpte |= PG_W;
        if (va < VM_MAX_USER_ADDRESS)
                newpte |= PG_U;
        if (pmap == &kernel_pmap)
                newpte |= pgeflag;

        /*
         * if the mapping or permission bits are different, we need
         * to update the pte.
         */
        if ((origpte & ~(PG_M|PG_A)) != newpte) {
                pmap_inval_interlock(&info, pmap, va);
                *pte = newpte | PG_A;
                pmap_inval_deinterlock(&info, pmap);
                if (newpte & PG_RW)
                        vm_page_flag_set(m, PG_WRITEABLE);
        }
        KKASSERT((newpte & PG_MANAGED) == 0 || (m->flags & PG_MAPPED));
        pmap_inval_done(&info);
        lwkt_reltoken(&vm_token);
}

/*
 * This code works like pmap_enter() but assumes VM_PROT_READ and not-wired.
 * This code also assumes that the pmap has no pre-existing entry for this
 * VA.
 *
 * This code currently may only be used on user pmaps, not kernel_pmap.
 */
void
pmap_enter_quick(pmap_t pmap, vm_offset_t va, vm_page_t m)
{
        pt_entry_t *pte;
        vm_paddr_t pa;
        vm_page_t mpte;
        vm_pindex_t ptepindex;
        pd_entry_t *ptepa;
        pmap_inval_info info;

        lwkt_gettoken(&vm_token);
        pmap_inval_init(&info);

        if (va < UPT_MAX_ADDRESS && pmap == &kernel_pmap) {
                kprintf("Warning: pmap_enter_quick called on UVA with kernel_pmap\n");
#ifdef DDB
                db_print_backtrace();
#endif
        }
        if (va >= UPT_MAX_ADDRESS && pmap != &kernel_pmap) {
                kprintf("Warning: pmap_enter_quick called on KVA without kernel_pmap\n");
#ifdef DDB
                db_print_backtrace();
#endif
        }

        KKASSERT(va < UPT_MIN_ADDRESS); /* assert used on user pmaps only */

        /*
         * Calculate the page table page (mpte), allocating it if necessary.
         *
         * A held page table page (mpte), or NULL, is passed onto the
         * section following.
         */
        if (va < VM_MAX_USER_ADDRESS) {
                /*
                 * Calculate pagetable page index
                 */
                ptepindex = pmap_pde_pindex(va);

                do {
                        /*
                         * Get the page directory entry
                         */
                        ptepa = pmap_pde(pmap, va);

                        /*
                         * If the page table page is mapped, we just increment
                         * the hold count, and activate it.
                         */
                        if (ptepa && (*ptepa & PG_V) != 0) {
                                if (*ptepa & PG_PS)
                                        panic("pmap_enter_quick: unexpected mapping into 2MB page");
//                              if (pmap->pm_ptphint &&
//                                  (pmap->pm_ptphint->pindex == ptepindex)) {
//                                      mpte = pmap->pm_ptphint;
//                              } else {
                                        mpte = pmap_page_lookup( pmap->pm_pteobj, ptepindex);
                                        pmap->pm_ptphint = mpte;
//                              }
                                if (mpte)
                                        mpte->hold_count++;
                        } else {
                                mpte = _pmap_allocpte(pmap, ptepindex);
                        }
                } while (mpte == NULL);
        } else {
                mpte = NULL;
                /* this code path is not yet used */
        }

        /*
         * With a valid (and held) page directory page, we can just use
         * vtopte() to get to the pte.  If the pte is already present
         * we do not disturb it.
         */
        pte = vtopte(va);
        if (*pte & PG_V) {
                if (mpte)
                        pmap_unwire_pte_hold(pmap, va, mpte, &info);
                pa = VM_PAGE_TO_PHYS(m);
                KKASSERT(((*pte ^ pa) & PG_FRAME) == 0);
                pmap_inval_done(&info);
                lwkt_reltoken(&vm_token);
                return;
        }

        /*
         * Enter on the PV list if part of our managed memory
         */
        if ((m->flags & (PG_FICTITIOUS|PG_UNMANAGED)) == 0) {
                pmap_insert_entry(pmap, va, mpte, m);
                vm_page_flag_set(m, PG_MAPPED);
        }

        /*
         * Increment counters
         */
        ++pmap->pm_stats.resident_count;

        pa = VM_PAGE_TO_PHYS(m);

        /*
         * Now validate mapping with RO protection
         */
        if (m->flags & (PG_FICTITIOUS|PG_UNMANAGED))
                *pte = pa | PG_V | PG_U;
        else
                *pte = pa | PG_V | PG_U | PG_MANAGED;
/*      pmap_inval_add(&info, pmap, va); shouldn't be needed inval->valid */
        pmap_inval_done(&info);
        lwkt_reltoken(&vm_token);
}

/*
 * Make a temporary mapping for a physical address.  This is only intended
 * to be used for panic dumps.
 */
/* JG Needed on x86_64? */
void *
pmap_kenter_temporary(vm_paddr_t pa, int i)
{
        pmap_kenter((vm_offset_t)crashdumpmap + (i * PAGE_SIZE), pa);
        return ((void *)crashdumpmap);
}

#define MAX_INIT_PT (96)

/*
 * This routine preloads the ptes for a given object into the specified pmap.
 * This eliminates the blast of soft faults on process startup and
 * immediately after an mmap.
 */
static int pmap_object_init_pt_callback(vm_page_t p, void *data);

void
pmap_object_init_pt(pmap_t pmap, vm_offset_t addr, vm_prot_t prot,
                    vm_object_t object, vm_pindex_t pindex, 
                    vm_size_t size, int limit)
{
        struct rb_vm_page_scan_info info;
        struct lwp *lp;
        vm_size_t psize;

        /*
         * We can't preinit if read access isn't set or there is no pmap
         * or object.
         */
        if ((prot & VM_PROT_READ) == 0 || pmap == NULL || object == NULL)
                return;

        /*
         * We can't preinit if the pmap is not the current pmap
         */
        lp = curthread->td_lwp;
        if (lp == NULL || pmap != vmspace_pmap(lp->lwp_vmspace))
                return;

        psize = x86_64_btop(size);

        if ((object->type != OBJT_VNODE) ||
                ((limit & MAP_PREFAULT_PARTIAL) && (psize > MAX_INIT_PT) &&
                        (object->resident_page_count > MAX_INIT_PT))) {
                return;
        }

        if (psize + pindex > object->size) {
                if (object->size < pindex)
                        return;           
                psize = object->size - pindex;
        }

        if (psize == 0)
                return;

        /*
         * Use a red-black scan to traverse the requested range and load
         * any valid pages found into the pmap.
         *
         * We cannot safely scan the object's memq unless we are in a
         * critical section since interrupts can remove pages from objects.
         */
        info.start_pindex = pindex;
        info.end_pindex = pindex + psize - 1;
        info.limit = limit;
        info.mpte = NULL;
        info.addr = addr;
        info.pmap = pmap;

        crit_enter();
        lwkt_gettoken(&vm_token);
        vm_page_rb_tree_RB_SCAN(&object->rb_memq, rb_vm_page_scancmp,
                                pmap_object_init_pt_callback, &info);
        lwkt_reltoken(&vm_token);
        crit_exit();
}

static
int
pmap_object_init_pt_callback(vm_page_t p, void *data)
{
        struct rb_vm_page_scan_info *info = data;
        vm_pindex_t rel_index;
        /*
         * don't allow an madvise to blow away our really
         * free pages allocating pv entries.
         */
        if ((info->limit & MAP_PREFAULT_MADVISE) &&
                vmstats.v_free_count < vmstats.v_free_reserved) {
                    return(-1);
        }
        if (((p->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL) &&
            (p->busy == 0) && (p->flags & (PG_BUSY | PG_FICTITIOUS)) == 0) {
                if ((p->queue - p->pc) == PQ_CACHE)
                        vm_page_deactivate(p);
                vm_page_busy(p);
                rel_index = p->pindex - info->start_pindex;
                pmap_enter_quick(info->pmap,
                                 info->addr + x86_64_ptob(rel_index), p);
                vm_page_wakeup(p);
        }
        return(0);
}

/*
 * Return TRUE if the pmap is in shape to trivially
 * pre-fault the specified address.
 *
 * Returns FALSE if it would be non-trivial or if a
 * pte is already loaded into the slot.
 */
int
pmap_prefault_ok(pmap_t pmap, vm_offset_t addr)
{
        pt_entry_t *pte;
        pd_entry_t *pde;
        int ret;

        lwkt_gettoken(&vm_token);
        pde = pmap_pde(pmap, addr);
        if (pde == NULL || *pde == 0) {
                ret = 0;
        } else {
                pte = vtopte(addr);
                ret = (*pte) ? 0 : 1;
        }
        lwkt_reltoken(&vm_token);
        return(ret);
}

/*
 *      Routine:        pmap_change_wiring
 *      Function:       Change the wiring attribute for a map/virtual-address
 *                      pair.
 *      In/out conditions:
 *                      The mapping must already exist in the pmap.
 */
void
pmap_change_wiring(pmap_t pmap, vm_offset_t va, boolean_t wired)
{
        pt_entry_t *pte;

        if (pmap == NULL)
                return;

        lwkt_gettoken(&vm_token);
        pte = pmap_pte(pmap, va);

        if (wired && !pmap_pte_w(pte))
                pmap->pm_stats.wired_count++;
        else if (!wired && pmap_pte_w(pte))
                pmap->pm_stats.wired_count--;

        /*
         * Wiring is not a hardware characteristic so there is no need to
         * invalidate TLB.  However, in an SMP environment we must use
         * a locked bus cycle to update the pte (if we are not using 
         * the pmap_inval_*() API that is)... it's ok to do this for simple
         * wiring changes.
         */
#ifdef SMP
        if (wired)
                atomic_set_long(pte, PG_W);
        else
                atomic_clear_long(pte, PG_W);
#else
        if (wired)
                atomic_set_long_nonlocked(pte, PG_W);
        else
                atomic_clear_long_nonlocked(pte, PG_W);
#endif
        lwkt_reltoken(&vm_token);
}



/*
 *      Copy the range specified by src_addr/len
 *      from the source map to the range dst_addr/len
 *      in the destination map.
 *
 *      This routine is only advisory and need not do anything.
 */
void
pmap_copy(pmap_t dst_pmap, pmap_t src_pmap, vm_offset_t dst_addr, 
          vm_size_t len, vm_offset_t src_addr)
{
        return;
#if 0
        pmap_inval_info info;
        vm_offset_t addr;
        vm_offset_t end_addr = src_addr + len;
        vm_offset_t pdnxt;
        pd_entry_t src_frame, dst_frame;
        vm_page_t m;

        if (dst_addr != src_addr)
                return;
#if JGPMAP32
        src_frame = src_pmap->pm_pdir[PTDPTDI] & PG_FRAME;
        if (src_frame != (PTDpde & PG_FRAME)) {
                return;
        }

        dst_frame = dst_pmap->pm_pdir[PTDPTDI] & PG_FRAME;
        if (dst_frame != (APTDpde & PG_FRAME)) {
                APTDpde = (pd_entry_t) (dst_frame | PG_RW | PG_V);
                /* The page directory is not shared between CPUs */
                cpu_invltlb();
        }
#endif
        pmap_inval_init(&info);
        pmap_inval_add(&info, dst_pmap, -1);
        pmap_inval_add(&info, src_pmap, -1);

        /*
         * critical section protection is required to maintain the page/object
         * association, interrupts can free pages and remove them from 
         * their objects.
         */
        crit_enter();
        for (addr = src_addr; addr < end_addr; addr = pdnxt) {
                pt_entry_t *src_pte, *dst_pte;
                vm_page_t dstmpte, srcmpte;
                vm_offset_t srcptepaddr;
                vm_pindex_t ptepindex;

                if (addr >= UPT_MIN_ADDRESS)
                        panic("pmap_copy: invalid to pmap_copy page tables\n");

                /*
                 * Don't let optional prefaulting of pages make us go
                 * way below the low water mark of free pages or way
                 * above high water mark of used pv entries.
                 */
                if (vmstats.v_free_count < vmstats.v_free_reserved ||
                    pv_entry_count > pv_entry_high_water)
                        break;
                
                pdnxt = ((addr + PAGE_SIZE*NPTEPG) & ~(PAGE_SIZE*NPTEPG - 1));
                ptepindex = addr >> PDRSHIFT;

#if JGPMAP32
                srcptepaddr = (vm_offset_t) src_pmap->pm_pdir[ptepindex];
#endif
                if (srcptepaddr == 0)
                        continue;
                        
                if (srcptepaddr & PG_PS) {
#if JGPMAP32
                        if (dst_pmap->pm_pdir[ptepindex] == 0) {
                                dst_pmap->pm_pdir[ptepindex] = (pd_entry_t) srcptepaddr;
                                dst_pmap->pm_stats.resident_count += NBPDR / PAGE_SIZE;
                        }
#endif
                        continue;
                }

                srcmpte = vm_page_lookup(src_pmap->pm_pteobj, ptepindex);
                if ((srcmpte == NULL) || (srcmpte->hold_count == 0) ||
                    (srcmpte->flags & PG_BUSY)) {
                        continue;
                }

                if (pdnxt > end_addr)
                        pdnxt = end_addr;

                src_pte = vtopte(addr);
#if JGPMAP32
                dst_pte = avtopte(addr);
#endif
                while (addr < pdnxt) {
                        pt_entry_t ptetemp;

                        ptetemp = *src_pte;
                        /*
                         * we only virtual copy managed pages
                         */
                        if ((ptetemp & PG_MANAGED) != 0) {
                                /*
                                 * We have to check after allocpte for the
                                 * pte still being around...  allocpte can
                                 * block.
                                 *
                                 * pmap_allocpte() can block.  If we lose
                                 * our page directory mappings we stop.
                                 */
                                dstmpte = pmap_allocpte(dst_pmap, addr);

#if JGPMAP32
                                if (src_frame != (PTDpde & PG_FRAME) ||
                                    dst_frame != (APTDpde & PG_FRAME)
                                ) {
                                        kprintf("WARNING: pmap_copy: detected and corrected race\n");
                                        pmap_unwire_pte_hold(dst_pmap, dstmpte, &info);
                                        goto failed;
                                } else if ((*dst_pte == 0) &&
                                           (ptetemp = *src_pte) != 0 &&
                                           (ptetemp & PG_MANAGED)) {
                                        /*
                                         * Clear the modified and
                                         * accessed (referenced) bits
                                         * during the copy.
                                         */
                                        m = PHYS_TO_VM_PAGE(ptetemp);
                                        *dst_pte = ptetemp & ~(PG_M | PG_A);
                                        ++dst_pmap->pm_stats.resident_count;
                                        pmap_insert_entry(dst_pmap, addr,
                                                dstmpte, m);
                                        KKASSERT(m->flags & PG_MAPPED);
                                } else {
                                        kprintf("WARNING: pmap_copy: dst_pte race detected and corrected\n");
                                        pmap_unwire_pte_hold(dst_pmap, dstmpte, &info);
                                        goto failed;
                                }
#endif
                                if (dstmpte->hold_count >= srcmpte->hold_count)
                                        break;
                        }
                        addr += PAGE_SIZE;
                        src_pte++;
                        dst_pte++;
                }
        }
failed:
        crit_exit();
        pmap_inval_done(&info);
#endif
}       

/*
 * pmap_zero_page:
 *
 *      Zero the specified physical page.
 *
 *      This function may be called from an interrupt and no locking is
 *      required.
 */
void
pmap_zero_page(vm_paddr_t phys)
{
        vm_offset_t va = PHYS_TO_DMAP(phys);

        pagezero((void *)va);
}

/*
 * pmap_page_assertzero:
 *
 *      Assert that a page is empty, panic if it isn't.
 */
void
pmap_page_assertzero(vm_paddr_t phys)
{
        vm_offset_t virt = PHYS_TO_DMAP(phys);
        int i;

        for (i = 0; i < PAGE_SIZE; i += sizeof(long)) {
            if (*(long *)((char *)virt + i) != 0) {
                panic("pmap_page_assertzero() @ %p not zero!\n", (void *)virt);
            }
        }
}

/*
 * pmap_zero_page:
 *
 *      Zero part of a physical page by mapping it into memory and clearing
 *      its contents with bzero.
 *
 *      off and size may not cover an area beyond a single hardware page.
 */
void
pmap_zero_page_area(vm_paddr_t phys, int off, int size)
{
        vm_offset_t virt = PHYS_TO_DMAP(phys);

        bzero((char *)virt + off, size);
}

/*
 * pmap_copy_page:
 *
 *      Copy the physical page from the source PA to the target PA.
 *      This function may be called from an interrupt.  No locking
 *      is required.
 */
void
pmap_copy_page(vm_paddr_t src, vm_paddr_t dst)
{
        vm_offset_t src_virt, dst_virt;

        src_virt = PHYS_TO_DMAP(src);
        dst_virt = PHYS_TO_DMAP(dst);
        bcopy((void *)src_virt, (void *)dst_virt, PAGE_SIZE);
}

/*
 * pmap_copy_page_frag:
 *
 *      Copy the physical page from the source PA to the target PA.
 *      This function may be called from an interrupt.  No locking
 *      is required.
 */
void
pmap_copy_page_frag(vm_paddr_t src, vm_paddr_t dst, size_t bytes)
{
        vm_offset_t src_virt, dst_virt;

        src_virt = PHYS_TO_DMAP(src);
        dst_virt = PHYS_TO_DMAP(dst);

        bcopy((char *)src_virt + (src & PAGE_MASK),
              (char *)dst_virt + (dst & PAGE_MASK),
              bytes);
}

/*
 * Returns true if the pmap's pv is one of the first
 * 16 pvs linked to from this page.  This count may
 * be changed upwards or downwards in the future; it
 * is only necessary that true be returned for a small
 * subset of pmaps for proper page aging.
 */
boolean_t
pmap_page_exists_quick(pmap_t pmap, vm_page_t m)
{
        pv_entry_t pv;
        int loops = 0;

        if (!pmap_initialized || (m->flags & PG_FICTITIOUS))
                return FALSE;

        crit_enter();
        lwkt_gettoken(&vm_token);

        TAILQ_FOREACH(pv, &m->md.pv_list, pv_list) {
                if (pv->pv_pmap == pmap) {
                        lwkt_reltoken(&vm_token);
                        crit_exit();
                        return TRUE;
                }
                loops++;
                if (loops >= 16)
                        break;
        }
        lwkt_reltoken(&vm_token);
        crit_exit();
        return (FALSE);
}

/*
 * Remove all pages from specified address space
 * this aids process exit speeds.  Also, this code
 * is special cased for current process only, but
 * can have the more generic (and slightly slower)
 * mode enabled.  This is much faster than pmap_remove
 * in the case of running down an entire address space.
 */
void
pmap_remove_pages(pmap_t pmap, vm_offset_t sva, vm_offset_t eva)
{
        struct lwp *lp;
        pt_entry_t *pte, tpte;
        pv_entry_t pv, npv;
        vm_page_t m;
        pmap_inval_info info;
        int iscurrentpmap;
        int save_generation;

        lp = curthread->td_lwp;
        if (lp && pmap == vmspace_pmap(lp->lwp_vmspace))
                iscurrentpmap = 1;
        else
                iscurrentpmap = 0;

        lwkt_gettoken(&vm_token);
        pmap_inval_init(&info);
        for (pv = TAILQ_FIRST(&pmap->pm_pvlist); pv; pv = npv) {
                if (pv->pv_va >= eva || pv->pv_va < sva) {
                        npv = TAILQ_NEXT(pv, pv_plist);
                        continue;
                }

                KKASSERT(pmap == pv->pv_pmap);

                if (iscurrentpmap)
                        pte = vtopte(pv->pv_va);
                else
                        pte = pmap_pte_quick(pmap, pv->pv_va);
                pmap_inval_interlock(&info, pmap, pv->pv_va);

                /*
                 * We cannot remove wired pages from a process' mapping
                 * at this time
                 */
                if (*pte & PG_W) {
                        pmap_inval_deinterlock(&info, pmap);
                        npv = TAILQ_NEXT(pv, pv_plist);
                        continue;
                }
                tpte = pte_load_clear(pte);

                m = PHYS_TO_VM_PAGE(tpte & PG_FRAME);

                KASSERT(m < &vm_page_array[vm_page_array_size],
                        ("pmap_remove_pages: bad tpte %lx", tpte));

                KKASSERT(pmap->pm_stats.resident_count > 0);
                --pmap->pm_stats.resident_count;
                pmap_inval_deinterlock(&info, pmap);

                /*
                 * Update the vm_page_t clean and reference bits.
                 */
                if (tpte & PG_M) {
                        vm_page_dirty(m);
                }

                npv = TAILQ_NEXT(pv, pv_plist);
                TAILQ_REMOVE(&pmap->pm_pvlist, pv, pv_plist);
                save_generation = ++pmap->pm_generation;

                m->md.pv_list_count--;
                TAILQ_REMOVE(&m->md.pv_list, pv, pv_list);
                if (TAILQ_EMPTY(&m->md.pv_list))
                        vm_page_flag_clear(m, PG_MAPPED | PG_WRITEABLE);

                pmap_unuse_pt(pmap, pv->pv_va, pv->pv_ptem, &info);
                free_pv_entry(pv);

                /*
                 * Restart the scan if we blocked during the unuse or free
                 * calls and other removals were made.
                 */
                if (save_generation != pmap->pm_generation) {
                        kprintf("Warning: pmap_remove_pages race-A avoided\n");
                        npv = TAILQ_FIRST(&pmap->pm_pvlist);
                }
        }
        pmap_inval_done(&info);
        lwkt_reltoken(&vm_token);
}

/*
 * pmap_testbit tests bits in pte's
 * note that the testbit/clearbit routines are inline,
 * and a lot of things compile-time evaluate.
 */
static
boolean_t
pmap_testbit(vm_page_t m, int bit)
{
        pv_entry_t pv;
        pt_entry_t *pte;

        if (!pmap_initialized || (m->flags & PG_FICTITIOUS))
                return FALSE;

        if (TAILQ_FIRST(&m->md.pv_list) == NULL)
                return FALSE;

        crit_enter();

        TAILQ_FOREACH(pv, &m->md.pv_list, pv_list) {
                /*
                 * if the bit being tested is the modified bit, then
                 * mark clean_map and ptes as never
                 * modified.
                 */
                if (bit & (PG_A|PG_M)) {
                        if (!pmap_track_modified(pv->pv_va))
                                continue;
                }

#if defined(PMAP_DIAGNOSTIC)
                if (pv->pv_pmap == NULL) {
                        kprintf("Null pmap (tb) at va: 0x%lx\n", pv->pv_va);
                        continue;
                }
#endif
                pte = pmap_pte_quick(pv->pv_pmap, pv->pv_va);
                if (*pte & bit) {
                        crit_exit();
                        return TRUE;
                }
        }
        crit_exit();
        return (FALSE);
}

/*
 * this routine is used to modify bits in ptes
 */
static __inline
void
pmap_clearbit(vm_page_t m, int bit)
{
        struct pmap_inval_info info;
        pv_entry_t pv;
        pt_entry_t *pte;
        pt_entry_t pbits;

        if (!pmap_initialized || (m->flags & PG_FICTITIOUS))
                return;

        pmap_inval_init(&info);

        /*
         * Loop over all current mappings setting/clearing as appropos If
         * setting RO do we need to clear the VAC?
         */
        TAILQ_FOREACH(pv, &m->md.pv_list, pv_list) {
                /*
                 * don't write protect pager mappings
                 */
                if (bit == PG_RW) {
                        if (!pmap_track_modified(pv->pv_va))
                                continue;
                }

#if defined(PMAP_DIAGNOSTIC)
                if (pv->pv_pmap == NULL) {
                        kprintf("Null pmap (cb) at va: 0x%lx\n", pv->pv_va);
                        continue;
                }
#endif

                /*
                 * Careful here.  We can use a locked bus instruction to
                 * clear PG_A or PG_M safely but we need to synchronize
                 * with the target cpus when we mess with PG_RW.
                 *
                 * We do not have to force synchronization when clearing
                 * PG_M even for PTEs generated via virtual memory maps,
                 * because the virtual kernel will invalidate the pmap
                 * entry when/if it needs to resynchronize the Modify bit.
                 */
                if (bit & PG_RW)
                        pmap_inval_interlock(&info, pv->pv_pmap, pv->pv_va);
                pte = pmap_pte_quick(pv->pv_pmap, pv->pv_va);
again:
                pbits = *pte;
                if (pbits & bit) {
                        if (bit == PG_RW) {
                                if (pbits & PG_M) {
                                        vm_page_dirty(m);
                                        atomic_clear_long(pte, PG_M|PG_RW);
                                } else {
                                        /*
                                         * The cpu may be trying to set PG_M
                                         * simultaniously with our clearing
                                         * of PG_RW.
                                         */
                                        if (!atomic_cmpset_long(pte, pbits,
                                                               pbits & ~PG_RW))
                                                goto again;
                                }
                        } else if (bit == PG_M) {
                                /*
                                 * We could also clear PG_RW here to force
                                 * a fault on write to redetect PG_M for
                                 * virtual kernels, but it isn't necessary
                                 * since virtual kernels invalidate the pte 
                                 * when they clear the VPTE_M bit in their
                                 * virtual page tables.
                                 */
                                atomic_clear_long(pte, PG_M);
                        } else {
                                atomic_clear_long(pte, bit);
                        }
                }
                if (bit & PG_RW)
                        pmap_inval_deinterlock(&info, pv->pv_pmap);
        }
        pmap_inval_done(&info);
}

/*
 *      pmap_page_protect:
 *
 *      Lower the permission for all mappings to a given page.
 */
void
pmap_page_protect(vm_page_t m, vm_prot_t prot)
{
        /* JG NX support? */
        if ((prot & VM_PROT_WRITE) == 0) {
                lwkt_gettoken(&vm_token);
                if (prot & (VM_PROT_READ | VM_PROT_EXECUTE)) {
                        pmap_clearbit(m, PG_RW);
                        vm_page_flag_clear(m, PG_WRITEABLE);
                } else {
                        pmap_remove_all(m);
                }
                lwkt_reltoken(&vm_token);
        }
}

vm_paddr_t
pmap_phys_address(vm_pindex_t ppn)
{
        return (x86_64_ptob(ppn));
}

/*
 *      pmap_ts_referenced:
 *
 *      Return a count of reference bits for a page, clearing those bits.
 *      It is not necessary for every reference bit to be cleared, but it
 *      is necessary that 0 only be returned when there are truly no
 *      reference bits set.
 *
 *      XXX: The exact number of bits to check and clear is a matter that
 *      should be tested and standardized at some point in the future for
 *      optimal aging of shared pages.
 */
int
pmap_ts_referenced(vm_page_t m)
{
        pv_entry_t pv, pvf, pvn;
        pt_entry_t *pte;
        int rtval = 0;

        if (!pmap_initialized || (m->flags & PG_FICTITIOUS))
                return (rtval);

        crit_enter();
        lwkt_gettoken(&vm_token);

        if ((pv = TAILQ_FIRST(&m->md.pv_list)) != NULL) {

                pvf = pv;

                do {
                        pvn = TAILQ_NEXT(pv, pv_list);

                        crit_enter();
                        TAILQ_REMOVE(&m->md.pv_list, pv, pv_list);
                        TAILQ_INSERT_TAIL(&m->md.pv_list, pv, pv_list);
                        crit_exit();

                        if (!pmap_track_modified(pv->pv_va))
                                continue;

                        pte = pmap_pte_quick(pv->pv_pmap, pv->pv_va);

                        if (pte && (*pte & PG_A)) {
#ifdef SMP
                                atomic_clear_long(pte, PG_A);
#else
                                atomic_clear_long_nonlocked(pte, PG_A);
#endif
                                rtval++;
                                if (rtval > 4) {
                                        break;
                                }
                        }
                } while ((pv = pvn) != NULL && pv != pvf);
        }
        lwkt_reltoken(&vm_token);
        crit_exit();

        return (rtval);
}

/*
 *      pmap_is_modified:
 *
 *      Return whether or not the specified physical page was modified
 *      in any physical maps.
 */
boolean_t
pmap_is_modified(vm_page_t m)
{
        boolean_t res;

        lwkt_gettoken(&vm_token);
        res = pmap_testbit(m, PG_M);
        lwkt_reltoken(&vm_token);
        return (res);
}

/*
 *      Clear the modify bits on the specified physical page.
 */
void
pmap_clear_modify(vm_page_t m)
{
        lwkt_gettoken(&vm_token);
        pmap_clearbit(m, PG_M);
        lwkt_reltoken(&vm_token);
}

/*
 *      pmap_clear_reference:
 *
 *      Clear the reference bit on the specified physical page.
 */
void
pmap_clear_reference(vm_page_t m)
{
        lwkt_gettoken(&vm_token);
        pmap_clearbit(m, PG_A);
        lwkt_reltoken(&vm_token);
}

/*
 * Miscellaneous support routines follow
 */

static
void
i386_protection_init(void)
{
        int *kp, prot;

        /* JG NX support may go here; No VM_PROT_EXECUTE ==> set NX bit  */
        kp = protection_codes;
        for (prot = 0; prot < 8; prot++) {
                switch (prot) {
                case VM_PROT_NONE | VM_PROT_NONE | VM_PROT_NONE:
                        /*
                         * Read access is also 0. There isn't any execute bit,
                         * so just make it readable.
                         */
                case VM_PROT_READ | VM_PROT_NONE | VM_PROT_NONE:
                case VM_PROT_READ | VM_PROT_NONE | VM_PROT_EXECUTE:
                case VM_PROT_NONE | VM_PROT_NONE | VM_PROT_EXECUTE:
                        *kp++ = 0;
                        break;
                case VM_PROT_NONE | VM_PROT_WRITE | VM_PROT_NONE:
                case VM_PROT_NONE | VM_PROT_WRITE | VM_PROT_EXECUTE:
                case VM_PROT_READ | VM_PROT_WRITE | VM_PROT_NONE:
                case VM_PROT_READ | VM_PROT_WRITE | VM_PROT_EXECUTE:
                        *kp++ = PG_RW;
                        break;
                }
        }
}

/*
 * Map a set of physical memory pages into the kernel virtual
 * address space. Return a pointer to where it is mapped. This
 * routine is intended to be used for mapping device memory,
 * NOT real memory.
 *
 * NOTE: we can't use pgeflag unless we invalidate the pages one at
 * a time.
 */
void *
pmap_mapdev(vm_paddr_t pa, vm_size_t size)
{
        vm_offset_t va, tmpva, offset;
        pt_entry_t *pte;

        offset = pa & PAGE_MASK;
        size = roundup(offset + size, PAGE_SIZE);

        va = kmem_alloc_nofault(&kernel_map, size, PAGE_SIZE);
        if (va == 0)
                panic("pmap_mapdev: Couldn't alloc kernel virtual memory");

        pa = pa & ~PAGE_MASK;
        for (tmpva = va; size > 0;) {
                pte = vtopte(tmpva);
                *pte = pa | PG_RW | PG_V; /* | pgeflag; */
                size -= PAGE_SIZE;
                tmpva += PAGE_SIZE;
                pa += PAGE_SIZE;
        }
        cpu_invltlb();
        smp_invltlb();

        return ((void *)(va + offset));
}

void *
pmap_mapdev_uncacheable(vm_paddr_t pa, vm_size_t size)
{
        vm_offset_t va, tmpva, offset;
        pt_entry_t *pte;

        offset = pa & PAGE_MASK;
        size = roundup(offset + size, PAGE_SIZE);

        va = kmem_alloc_nofault(&kernel_map, size, PAGE_SIZE);
        if (va == 0)
                panic("pmap_mapdev: Couldn't alloc kernel virtual memory");

        pa = pa & ~PAGE_MASK;
        for (tmpva = va; size > 0;) {
                pte = vtopte(tmpva);
                *pte = pa | PG_RW | PG_V | PG_N; /* | pgeflag; */
                size -= PAGE_SIZE;
                tmpva += PAGE_SIZE;
                pa += PAGE_SIZE;
        }
        cpu_invltlb();
        smp_invltlb();

        return ((void *)(va + offset));
}

void
pmap_unmapdev(vm_offset_t va, vm_size_t size)
{
        vm_offset_t base, offset;

        base = va & ~PAGE_MASK;
        offset = va & PAGE_MASK;
        size = roundup(offset + size, PAGE_SIZE);
        pmap_qremove(va, size >> PAGE_SHIFT);
        kmem_free(&kernel_map, base, size);
}

/*
 * perform the pmap work for mincore
 */
int
pmap_mincore(pmap_t pmap, vm_offset_t addr)
{
        pt_entry_t *ptep, pte;
        vm_page_t m;
        int val = 0;
        
        lwkt_gettoken(&vm_token);
        ptep = pmap_pte(pmap, addr);

        if (ptep && (pte = *ptep) != 0) {
                vm_offset_t pa;

                val = MINCORE_INCORE;
                if ((pte & PG_MANAGED) == 0)
                        goto done;

                pa = pte & PG_FRAME;

                m = PHYS_TO_VM_PAGE(pa);

                /*
                 * Modified by us
                 */
                if (pte & PG_M)
                        val |= MINCORE_MODIFIED|MINCORE_MODIFIED_OTHER;
                /*
                 * Modified by someone
                 */
                else if (m->dirty || pmap_is_modified(m))
                        val |= MINCORE_MODIFIED_OTHER;
                /*
                 * Referenced by us
                 */
                if (pte & PG_A)
                        val |= MINCORE_REFERENCED|MINCORE_REFERENCED_OTHER;

                /*
                 * Referenced by someone
                 */
                else if ((m->flags & PG_REFERENCED) || pmap_ts_referenced(m)) {
                        val |= MINCORE_REFERENCED_OTHER;
                        vm_page_flag_set(m, PG_REFERENCED);
                }
        } 
done:
        lwkt_reltoken(&vm_token);
        return val;
}

/*
 * Replace p->p_vmspace with a new one.  If adjrefs is non-zero the new
 * vmspace will be ref'd and the old one will be deref'd.
 *
 * The vmspace for all lwps associated with the process will be adjusted
 * and cr3 will be reloaded if any lwp is the current lwp.
 */
void
pmap_replacevm(struct proc *p, struct vmspace *newvm, int adjrefs)
{
        struct vmspace *oldvm;
        struct lwp *lp;

        crit_enter();
        oldvm = p->p_vmspace;
        if (oldvm != newvm) {
                p->p_vmspace = newvm;
                KKASSERT(p->p_nthreads == 1);
                lp = RB_ROOT(&p->p_lwp_tree);
                pmap_setlwpvm(lp, newvm);
                if (adjrefs) {
                        sysref_get(&newvm->vm_sysref);
                        sysref_put(&oldvm->vm_sysref);
                }
        }
        crit_exit();
}

/*
 * Set the vmspace for a LWP.  The vmspace is almost universally set the
 * same as the process vmspace, but virtual kernels need to swap out contexts
 * on a per-lwp basis.
 */
void
pmap_setlwpvm(struct lwp *lp, struct vmspace *newvm)
{
        struct vmspace *oldvm;
        struct pmap *pmap;

        crit_enter();
        oldvm = lp->lwp_vmspace;

        if (oldvm != newvm) {
                lp->lwp_vmspace = newvm;
                if (curthread->td_lwp == lp) {
                        pmap = vmspace_pmap(newvm);
#if defined(SMP)
                        atomic_set_int(&pmap->pm_active, mycpu->gd_cpumask);
                        if (pmap->pm_active & CPUMASK_LOCK)
                                pmap_interlock_wait(newvm);
#else
                        pmap->pm_active |= 1;
#endif
#if defined(SWTCH_OPTIM_STATS)
                        tlb_flush_count++;
#endif
                        curthread->td_pcb->pcb_cr3 = vtophys(pmap->pm_pml4);
                        curthread->td_pcb->pcb_cr3 |= PG_RW | PG_U | PG_V;
                        load_cr3(curthread->td_pcb->pcb_cr3);
                        pmap = vmspace_pmap(oldvm);
#if defined(SMP)
                        atomic_clear_int(&pmap->pm_active, mycpu->gd_cpumask);
#else
                        pmap->pm_active &= ~1;
#endif
                }
        }
        crit_exit();
}

#ifdef SMP

/*
 * Called when switching to a locked pmap
 */
void
pmap_interlock_wait(struct vmspace *vm)
{
        struct pmap *pmap = &vm->vm_pmap;

        if (pmap->pm_active & CPUMASK_LOCK) {
                while (pmap->pm_active & CPUMASK_LOCK) {
                        cpu_pause();
                        cpu_ccfence();
                        lwkt_process_ipiq();
                }
        }
}

#endif

vm_offset_t
pmap_addr_hint(vm_object_t obj, vm_offset_t addr, vm_size_t size)
{

        if ((obj == NULL) || (size < NBPDR) || (obj->type != OBJT_DEVICE)) {
                return addr;
        }

        addr = (addr + (NBPDR - 1)) & ~(NBPDR - 1);
        return addr;
}

/*
 * Used by kmalloc/kfree, page already exists at va
 */
vm_page_t
pmap_kvtom(vm_offset_t va)
{
        return(PHYS_TO_VM_PAGE(*vtopte(va) & PG_FRAME));
}